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AN ATLAS 



OF 






ASTRONOMY 



AN ATLAS 



OF 



ASTRONOMY 



A SERIES OF SEVENTY-TWO PLATES, 



WITH INTRODUCTION AND INDEX. 



BY 

SIR ROBERT STAWELL BALL, LL.D., F.R.S., 

LOWNDEAN PROFESSOR OF ASTRONOMY AND GEOMETRY IN THE UNIVERSITY OF CAMBRIDGE. 

Author of " Star land." 



'1 V I , 



* o j o ■ 



> o •• , ,, ' '» ) > > 



NEW YORK : 
D. APPLETON AND COMPANY. 

1892. 



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• • • 4 



PREFACE. 



I have been frequently asked by readers of my little book, " Starland," to recommend 
a set of maps which would facilitate their study of the Heavens. It happened that 
while I was answering some of these queries, I received an invitation from the enter- 
prising publishers of the present work to prepare a new Astronomical Atlas. This 
seemed an opportunity for attempting to introduce some features that I could not 
find in any one of the existing Atlases, excellent though many of them doubtless are. 
In the first instance, I only thought of preparing a work which should meet the 
wants of beginners in Astronomy. However, the scheme gradually developed, and at 
length it appeared that, while the wants of my young friends were suitably supplied, 
it was possible to give the Atlas a scope that would make it more widely serviceable 
than if it were intended merely as a handbook to accompany so elementary a book as 
" Starland." The result is the present work, comprising seventy-two Plates, with the 
necessary explanatory matter. 

In the introduction will be found sufficient information about the several Plates, 
and the methods of using them. It is, however, desirable in this place to draw 
attention to certain characteristics of the work, and to make my acknowledgments 
to the friends who have kindly assisted me. 

The four charts for Sun Spot observations, Plates 19 and 22 inclusive, are based 
on drawings due to Professor Arthur W. Thomson, whose assistance I was glad to 
obtain. We introduced, however, some modifications, and the charts as actually 
presented have been drawn by Dr. Rambaut. I have to thank Mr. H. H. Turner, 
Chief Assistant of Greenwich Observatory, for the kindness with which he has 
supplied the Table of Heliographic Longitude of the Centre of the Sun's Disc (see 
p. 20). I would refer in this connection to the admirable annual known as the 
Companion to the Observatory. 

My thanks must next be offered to Mr. Thomas Gwyn Elger, for complying with 
my request that he would prepare the set of Moon Charts forming Plates 23 to 38 
inclusive. The series contains careful charts of the lunar formations ; it also gives a 
picture of the Moon for nearly every age at which it can be satisfactorily observed, 
up to the time of the full. Each of these pictures is furnished with a key and index 
of names, and it is believed that students of our satellite will find these plates of 
much service in identifying the various lunar objects. 



Vi PREFACE. 

Another feature of the present work consists of what I have designated the 
" Index to Planets." The identification of these bodies is often a matter of difficulty 
to a beginner ; his Maps will enable him to name the Stars, but the shifting positions 
of the Planets are apt to give trouble. I have removed this difficulty for the next 
decade, at all events, by providing a simple method of learning in a few seconds the 
approximate position of every important planet. The " Index to Planets " will enable 
the reader to discover what Planet it is at which he is looking, to find out the time 
to seek for any Planet he wants to observe, or to ascertain the place where it is to 
be found. The Table of Planetary Phenomena, up to a.d. 1902, was computed by 
Mr. J. Hind Bell. 

Perhaps I ought to say a few words as to a certain omission from this Atlas, 
though the size to which it has already swollen seems to render any apology for its 
not being larger unnecessary. It contains no plates showing the spectra of the 
heavenly bodies. An entire Atlas, which must be no small one either, would be 
necessary to do any justice to this great branch of astronomical work ; accordingly, 
1 came to the conclusion that it had better be altogether omitted. 

The drawings of the planet Jupiter, on Plate 10, have been copied from Dr. O. 
Lohse's observations, in the third volume of the publications of the Astrophysi- 
kalische Observatorium, at Potsdam. I am indebted to Professor H. C. Yogel for 
his kindness in placing this beautiful work at my disposal. The ideal tail of a comet, 
represented on the same Plate, is a sketch by Professor Bredichin. I owe the use of 
this figure to Dr. R. Copeland and Dr. J. L. E. Dreyer. 

For the pictures of Saturn, forming Plate 11, I am indebted to the courtesy of 
the late Mr. R. A. Proctor's executors, and his publishers — Messrs. Longmans & Co. 
These views form the frontispiece to Proctor's well-known treatise on " Saturn and 
its system." 

The Map of the Pleiades, on Plate 12, showing the remarkable nebula associated 
with that group of stars, is due to the Messrs. Henry. For the catalogue of the posi- 
tions of the stars in this cluster (see pp. 11-12) I have depended on Dr. Elkin's elaborate 
researches. 

Plate 14, representing the great Nebula in Andromeda, and the great Nebula 
in Orion, have been derived from Dr. Isaac Roberts' remarkable photographs of these 
bodies. 

Plate 9 contains a chart of Mars, drawn by Dr. Rambaut. I have to acknow- 
ledge the kindness with which Mr. Green and Mr. Knobel permitted me to make use 
of their beautiful drawings of the planet. 



PREFACE. 



Vll 



Plate 15, representing Donati's Comet, and Plate 16, representing Coggia's 
Comet, have been taken from that repertory of exquisite astronomical representation, 
The Annals of the Harvard College Observatory. For this and many other kind- 
nesses my acknowledgments are due to Professor Pickering. 

To the Harvard College Observatory I am also indebted for the view of the solar 
prominences on Plate 17. The photograph of the Corona, on the same plate, was 
contributed by Mr. A. A. Common. The view of the sun spot, also on the same 
plate, I copied from Knowledge, by permission of the editor, Mr. A. Cowper Ranyard, 
whose kindness on this, as on other occasions, I am here glad to acknowledge. 

The selection of subjects for the plates, and the method in which they should be 
treated, has received much consideration for more than four years. Summarizing 
the work, it may be said that Mr. Elger has specially drawn sixteen of the plates, 
that Dr. Rambaut has specially drawn forty-nine, and that the remainder, to the 
number of seven, have been obtained from other sources. I ought, however, to add 
that Plate 18, though drawn by Dr. Rambaut, was suggested by a somewhat similar 
picture in Secchi's Le Soleil. 

Not only two-thirds of the plates, but also a considerable part of the letterpress 
forming the introduction, are due to Dr. Rambaut, whose cordial co-operation has 
been of the utmost value to me in all parts of the work. 

In the revision of the entire volume, I have once again to acknowledge the 
valuable aid of my esteemed friend, Rev. M. H. Close. 

R. S. B. 
Observatory, Co. Dublin, 

September ', 1892. 



CONTENTS OF INTRODUCTION. 



PAGE 

Chap. 1.— The General Maps . . . - . . , . , ] 

II.— The Solar Maps. 17 
III.— The Lunar Maps .,........' 22 

IV.— The Monthly Maps . 30 

V.— The Index to the Planets . . . . , , .33 

VI.— The Star Maps ....... , . . S9 

VII.— Select Telescopic Objects. ..,.»(.. 46 



LIST OF PLATES. 



PLATE 

The Circles of the Sphere, Refraction, and Parallax ... ... 1 

The Inner Planets ........... 2 

The Outer Planets ........... 3 

The Planetary System .......... 4 

The Seasons and the Tides .......... 5 

Systems of Satellites. .......... 6 

Eclipses, and Phases of the Moon ......... 7 

Phases of the Planets, and of the Rings of Saturn ...... 8 

A Chart of Mars ............ 9 

Jupiter and Comets ........... 10 

Saturn ............. 11 

The Pleiades ............ 12 

Orbit of a Double Star ......... 13 

Nebula ............. 14 

The Comet of Donati, October 5th, 1858 . ....... 15 

The Comet of Coggia, 1874 ....... . 16 

Solar Phenomena ......... . . 17 

Paths of Spots across the Sun's Disc ..... 18 

Chart for Sun-Spot Observation — No. 1 . . . . . • • .19 

No. 2 ... . . 20 

No. 3 ... ... 21 

No. 4 22 

Chart of the Moon — 1st Quadrant ........ 



4th Day 
5th Day 
6th Day 
7th Day 



23 



„ ,, 2nd Quadrant .... 24 

,, ,, 3rd Quadrant ..... ... 25 

„ „ 4th Quadrant ......... 26 

The Moon— 3rd Day ....<•• • • 27 



28 
29 
30 
31 



CONTENTS. 



XI. 



The Moon— 8th Day 
9th Day 
10th Day 
11th Day 
12th Day 
13th Day 
14th Day 
Star Map — January 
February 
March 
April 
May . 
June 
July . 
August 
September 
October . 
November 
December 
General Star Map — Section I. 

Section II. 

Section IIT. 

Section TV. 

Section V. 

Section VI. 

Section VI I. 

Section VIII. . 

Section IX. 

Section X. 

Section XI. 

Section XII. . 

Section XIII. 

Section XIV. . 

Section XV. 

Section XVI. . 

Section XVII. 

Section XVIII. 

Section XIX. 

Section XX. . 
Northern Index Map 
Southern Index Map 



plate 
32 

. 33 

34 
. 35 

36 
. 37 

38 
. 39 

40 
. 41 

42 
. 43 

44 
. 45 

46 
• 47 

48 
. 49 

50 
. 51 

52 
. 53 

54 
. 55 

56 
. 57 

58 
. 59 

60 
. 61 

62 
. 63 

64 
. 65 

66 
, 67 

68 
. 69 

70 
, 71 

72 



Alphabetical Index, 



INTRODUCTION. 



CHAPTER l.—THE GENERAL MAPS. 



Plate 1. 
THE CIRCLES OF THE SPHERE, REFRACTION, AND PARALLAX. 

Fig. 1. — The observer is supposed to be placed at the centre of this figure, and the 
sphere which surrounds him is the Sphere of the Heavens. The nomenclature of the different 
parts is given in the margin of the plate, and the meaning of other technical terms used here 
or elsewhere will be found in the Index. 

The Bight Ascension of a celestial object is the arc, usually expressed in time, measured 
on the Equator from the point X, at the intersection of the Ecliptic and the Equator, to 
where the Meridian through the object cuts the Equator. The Declination of the object is 
the arc on this Meridian between the object and the Equator. 

Fig. 2. — The refraction of light in the atmosphere raises the apparent place of a celestial 
object towards the zenith. The line marked "true direction" shows the curved path of a ray 
of light as it traverses the air. When the ray enters the eye, the direction that it has at the last 
part of its journey is marked as the "apparent direction." The dotted lines show an extreme 
case in which a ray of light proceeding from below the horizon is so refracted as to raise the 
apparent position of the body above the horizon. Instances of this occur both at sunrise and 
sunset, for the Sun, when appearing to be touching the horizon, lies entirely below it. The 
actual amount of refraction has been necessarily exaggerated in the diagram. The angle 
through which a body is apparently thrown upwards towards the zenith increases with the 
zenith distance. 

The following Table gives the amount of the refraction at different zenith distances from 
0° to 90°, when the height of the barometer is 30 inches and the temperature 50° : — 







Table of 


Refractions. 






Apparent 




Apparent 




Apparent 




Zenith 


Refraction. 


Zenith 


Refraction. 


Zenith 


Refraction. 


Distance. 




Distance. 




Distance. 









o-o 


o 

35 


' 40*8 


o 

70 


2 38'8 


5 


51 


40 


48-9 


75 


3 34 3 


10 


10-3 


45 


58-2 


80 


5 19'8 


15 


15'6 


50 


1 93 


85 


9 54-8 


20 


21*2 


55 


1 23-4 


87 


14 28-1 


25 


27*2 


60 


1 40*6 


89 


24 21-2 


30 


33'6 


65 


2 4-3 


90 


33 46 3 



2 INTRODUCTION. 

Fig. 3. — Diurnal Parallax is the angle between the direction of a celestial object as 
seen from the Earth's surface, and the direction of the object if it could be seen from the 
centre of the Earth. To the remarks that will be found on the plate, it is necessary to 
add that the apparent place of a star as seen from the Earth is, strictly speaking, different 
from that in which it would be seen by an observer at the Sim. The angle subtended 
by the radius of the Earth's orbit at the Star is known as the Annual Parallax. It is 
generally too small a quantity to be measurable. 



Plate 2. 



THE INNER PLANETS. 

In the attempt to represent the orbits of celestial bodies on maps or charts, it must 
always be remembered that, except in the case of orbits which happen to lie in the same plane, 
it is impossible to depict on any drawing the veritable position of more than one. \Ve are 
obliged to resort to some process of a more or less artificial character. For instance, we take 
the plane of the Ecliptic, that is, the Earth's orbit, as the plane of the paper, and then we 
simply draw on it the orbits of the other bodies, notwithstanding that their planes are inclined 
to the Ecliptic. The points in which the real orbit passes through the plane of represent- 
ation are called the Nodes, the ascending node being that at which the planet passes from 
the southerly to the northerly side of the plane. Each orbit may be conceived to be turned 
around its line of nodes till its plane coincides with the Ecliptic. It is thus that Plate 2 is 
produced. 

The path which every planet describes is an ellipse, and the Sun is situated in one of the 
foci. The line P A through the 
two foci is the axis major of the 
ellipse. It is bisected in at 
the centre of the orbit. The line 
X Y through 0, perpendicular to 
A P, is the axis minor. The 
semi-axis major P is the mean 
distance of the planet from the 
Sun. The eccentricity of the 
ellipse is the ratio of S to P. 
The point P. nearest the Sun, is 
the Perihelion of the orbit. The 
point A, remotest from the Sun, 
is the Aphelion of the orbit. 
The points A and P are known 
as the Apses. The time that the 
planet takes to go round its orbit is the Periodic Time. The smaller the ratio of S to P, 
the less is the eccentricity of the orbit, and the more does the ellipse resemble a circle. The 
orbits of the more important planets have small eccentricity. 

The following extract from the Nautical Almanac will be useful in connection with the 
present plate, as well as in other parts of this Atlas. 




THE ELLIPSE. 



INTRODUCTION. 



Explanation of Astronomical Symbols and Abbreviations. 



% The Sun. 
d The Moon. 
£ Mercury. 
? Venus. 
© or 5 The Earth. 

h Hours. 

m Minutes of Time. 

s Seconds of Time. 

0. r Aries - 

1. « Taurus - 
II. n Gemini - 

III. <?d Cancer - 



o 

30 
60 
90 



6 

11 

¥ 

1 1 1 



Mars. 

Jupiter. 

Saturn. 

Uranus. 

Neptune. 



Degrees. 



Minutes of Arc. 
Seconds of Arc. 



IV. 

V. 

VI. 

VII. 



si Leo. - 

ft)? Virgo. 

^ Libra - 

in Scorpio 



120 

150 
180 
210 



6 Conjunction. 

□ Quadrature. 

c? Opposition. 

Si Ascending Node, 

y Descending Node. 



N. North. 
E. East. 



S. South. 
W. West. 



VIII. J Sagittarius 
IX. >? Capricornus 
X. xz Aquarius - 
XL j{ Pisces 



240 
270 
300 
33o 



The orbits of the planets Mercury, Venus, Earth, and Mars are represented in this plate, 
and for illustrating the use of it we take the orbit of Mercury. The point A is the Aphelion 
where the planet is most distant from the Sun. The' next point marked is the Ascending 
Node si t where the orbit comes through the plane of the paper, the inclination being 7° 0', as 
given in the table in the upper right hand corner of the map. P is the Perihelion, where Mercury 
is nearest the Sun. For a complete revolution this planet requires a period of 87 '969 days. 
Similar remarks apply to the other orbits. Thus, for instance, Mars, the outermost of the four 
planets shown in this figure, revolves in the period of 686*951 days. Its Perihelion is marked 
P, and Aphelion A, the Ascending Node is Si, and the inclination is 1° 51'. The inclinations 
of the cometary orbits are given in the right hand lower corner of the plate. The orbits 
of the three following comets are drawn, Biela's Comet, Comet I. 1866, and Comet III. 1862. 
These have been chosen because they possess the additional interest of being the paths of the 
three chief meteor swarms. The famous showers of " Leonids," which appear from November 
12th to 14th, at intervals of about 33 years, move in the track of Comet 1. 1866. The " Andro- 
medes," or meteors of November 27th, have the same orbit as Biela's Comet, and the 
" Perseids " pursue the course of Comet III. 1862. In the case of each of the cometary orbits 
the Descending Node has been marked on the plate, as it is at this Node that the Earth 
meets the associated meteor swarm. 



Plate 3. 
THE OUTER PLANETS. 

The innermost orbit on this plate is that of Mars, for those belonging to planets still closer 
to the Sun would be too small to be shown in a figure of the scale necessary for the outer 
planets. Next to Mars comes the zone of minor planets, the innermost represented being 
Medusa, with a period of 3*12 years, and the outermost, Hilda, with a period of 7'90 years. 
Beyond these lie the orbits of Jupiter, Saturn, Uranus, and Neptune. The positions of the 
several Perihelions and Aphelions are marked, as are also the Ascending Nodes. 

The orbit of Encke's Comet is interesting as being the smallest of cometary orbits, 
as well as on other grounds. Plate 3 contains also a more complete representation of the 
orbit of Biela's Comet than was possible on Plate 2, where a part of the same ellipse was 
shown. Halley's Comet revolves in a larger elliptic orbit, with a period of about 76 years, 
while a portion of the remarkable parabolic orbit of the great Comet of 1882 is also indicated. 



INTRODUCTION. 



Plate 4. 

THE PLANETARY SYSTEM. 

Plate 4 is intended to show the comparative sizes of the different planets. The oppor- 
tunity has, however, been taken to add some further information with regard to these members 
of the solar system. The largest planet is Jupiter, with an equatorial diameter of 87,500 miles. 
Its departure from the circular outline is indicated on the plate, and the oblateness of the 
planet is thus shown. The polar diameter of Jupiter is 82,500 miles. The period of rotation 
is taken to be 9h. 55m. The inclination of the equator of Jupiter to the Ecliptic is 3° 5'. The 
equatorial diameter of Saturn is 74,000 miles, and his polar diameter is 68,000. The period 
of rotation of the planet is lOh. 14m. Os., and the inclination of his equator to the Ecliptic 
is 28° 10'. A plan of the ring system surrounding Saturn is also shown, and the dimensions 
of the several concentric circles are set down. Thus the radius of Saturn is 37,000 miles, 
and the radius of the outer margin of the outer ring is 85,000 miles. 

The facts as regards the other planets are as follows : — 
Names. 

Neptune 

Uranus 

Earth 

Venus 

Mars 

Mercury 

The periods of rotation for Venus and Mercury are probably identical with their periods 
of revolution, viz., 224*701 days and 87*969 days respectively. 



Mean Diameters 
in miles. 


Axial Rotation. 


Inclination of Equator 
to Ecliptic. 


34,500 
31,700 
7,918 
7,660 
4,200 
2,992 


Unknown 

Unknown 
23 h - 56 111 - 4 8 - 

See below 
24 37 33 

See below 


35° V 

101 ? 
23 28 

? 
28 42 

? 



Plate 5. 

THE SEASONS AND THE TIDES. 

The figure in the right-hand upper corner shows the apparent diurnal path of the Sun at 
different seasons of the year. The latitude at which the observer is stationed is supposed to 
be that of the centre of the British Isles. On the shortest day, 21st December, the apparent 
motion of the Sun is in the Tropic of Capricorn, of which only a small part is above the horizon. 
On the 21st June, the longest day, the Sun moves in the Tropic of Cancer, of which only a 
small part is below the horizon. 

The central figure shows the Earth, in different positions in its orbit, as it would be viewed 
from an elevation of 20° above the Ecliptic. It must of course be understood that in these 
figures the size of the Earth is enormously exaggerated in proportion to the size of its orbit. 
This figure is intended to explain the significance of the circles by which the Earth is divided 
into zones. On the 21st June all the region inside the Arctic Circle has no night, while 
the entire region within the Antarctic Circle, lying entirely within the shaded hemisphere, 
has no day. By the ensuing 21st December the conditions are interchanged. The terrestrial 
tropics are the two circles of north and south latitude on the Earth, over which the Sun is 
vertical on the 21st June and 21st December respectively. The vernal equinox is on the 21st 
March, and the autumnal equinox on the 23rd September. On both these dates day and night 



INTRODUCTION. 5 

are equal all over the Earth. The various circles on our globe are further illustrated by the 
figure in the lower corner right-hand side, in which the Earth in its orbit is supposed to be viewed 
from the pole of the Ecliptic, that is, as it would be seen by an observer in that point of the 
heavens indicated by a perpendicular to the plane of the Earth's orbit drawn through the Sun. 

The apparent annual path of the Sun in the heavens is shown in the top figure, left-hand 
side. It is specially intended to explain the significance of the Equinoxes. On the 21st March 
the Sun ascends from the south of the Equator to the north, and on the 23rd September it 
descends from the north of the Equator to the south. 

Tides are the disturbances in the level of the ocean arising from the attraction of the 
Moon and the Sun. The figure at the lower part of the plate illustrates the remarkable fact 
that there are protuberant masses of water at opposite sides of the globe. Though these are 
caused by the tide-producing body, they are not necessarily, nor indeed generally, in line with 
it. The Moon is a much more efficient tide -producing agent than the Sun. The figure at the 
top of the plate is to explain the expressions spring and neap tides. At the time of New Moon, 
and at Full Moon, the tides raised by the Sun and Moon conspire, and an exceptionally high 
tide is produced, which is called a spring tide. At the First or Last Quarter Moon, the Sun 
tends to produce low water when and where the Moon tends to produce high water, and conse- 
quently, the result is a small or neap tide. 



Plate 6. 



SYSTEMS OF SATELLITES. 



This plate exhibits the relative dimensions of the orbits of the systems of satellites 
attending certain of the planets. With the exception of the system surrounding Mars, which 
is on a scale twenty times as large as the rest, the orbits are all laid down on a uniform scale of 
half a million miles to the inch. The periods of revolution of the satellites around their pri- 
maries are also marked on the orbits approximately. More complete numerical information 
than it has been found convenient to represent on the map is given in the following tables. 

The Moon. 

Mean distance from the Earth is 238,000 miles. The time of revolution around the Earth 
is 27 days 7 hrs. 43 mins. 11 sees. 

The Satellites of Maes. 



Name. 

Phobos . . . 


Mean Distance from Centre 
of Mars. 

5,800 miles 




Periodic Time, 
hrs. mins. sees, 
7 39 14 


Deimos . . . 


14,500 „ 




30 17 54 




The Satellites of Jupiter. 




Name. 

I 

II 

III. . 


Mean Distance from Centre 
of Jupiter. 

262,000 miles 
417,000 „ 
664,000 „ 


Days 

1 
3 

7 


Periodic Time. 

hrs. mins. sees. 

18 27 34 

13 13 42 

3 42 33 


IV. . 


1,170,000 „ 


16 


16 32 11 





INTRODUCTION. 










The Satellites of Saturn. 






Name. 

Mimas 

Enceladus 


Mean Distance from Centre 
of Saturn. 

118,000 miles 

152,030 „ 


Days 

] 


Periodic Time. 

hrs. mins. 

22 37 

8 53 


sees. 

27'9 

6-7 


Tethys 
Dione 


188,000 „ 

241,000 „ 


1 

2 


21 18 
17 41 


257 
8'9 


Rhea 


337,000 „ 


4 


12 25 


10*8 


Titan 


781,000 „ 


15 


22 41 


25-2 


Hyperion 

lapetus 


946,000 ., 

2,280,000 „ 


21 
79 


7 7 
7 54 


40-8 
40*4 




The Satellites of Uranus. 






Name. 

Ariel 
Umbriel 
Titania . . . 


Mean Distance from Centre 
of Uranus. 

119,000 miles 

166,000 „ 

272,000 „ 





Periodic Time. 
Days hrs. mins. 

2 12 29 

4 3 27 

8 16 56 


Oberon . . . 


363,000 „ 




13 11 


7 




The Satellite of Neptune. 






Anonymous 


Mean Distance from Centre 
of Neptune. 

220,000 miles 





Periodic Time. 

Days hrs. mins 

5 21 3 



Plate 7. 
PHASES OF THE MOON, AND SOLAR AND LUNAR ECLIPSES. 

Relative positions of Sun, Earth, and Moon. The hemisphere of the Moon that is directed 
towards the Sun is of course brilliantly lighted, and the corresponding phases of the Moon are 
caused by the varying proportions in which the illuminated hemisphere is directed towards the 
Earth. 

When the Moon comes between the Earth and the Sun, a Total Eclipse of the Sun takes 
place on those regions of the Earth which the Moon's shadow covers. At those places where 
the Moon's disc does not altogether conceal that of the Sun a Partial Eclipse of the Sun is seen. 
The case of minimum totality arises when the vertex of the conical shadow of the Moon just 
reaches the Earth. If the shadow of the Moon does not reach the Earth, then an Annular 
Eclipse of the Sun takes place. 

An Eclipse of the Moon arises from the entry of the Moon into the shadow of the Earth. 
In the majority of revolutions the Moon passes quite clear of the Earth's Shadow, and there 
is no Ecfy^se ; when the Moon is entirely immersed in the Earth's shadow, there is a Toted 
Eclipse ; and when it is partially immersed there is a Partial Eclipse. These three cases are 
illustrated at the foot of the plate. 



Plate 8. 

PHASES OF THE PLANETS. 

This plate exhibits the appearances of the planets Mars, Venus, and Saturn when occu- 
pying different parts of their orbits. A reference to Plate 2 makes it clear that the distance 
between the Earth and Mars must vary considerably at different dates, according to the positions 



INTRODUCTION. 7 

which the bodies occupy in their paths around the Sun. Of course, if the orbits were both 
circular, it is clear that the greatest possible separation between the two bodies would be 
attained at every conjunction, that is to say, whenever the Earth, Sun, and Planet are in a 
straight line (at least in their projected orbits), the Earth and Planet being at opposite sides 
of the Sun. The same diagram makes it plain that the least distance apart would occur at 
every opposition, that is, whenever the three bodies, as represented in their projected orbits, 
were in a straight line, with the Earth in the middle. 

The eccentricity of the orbit of Mars considerably modifies the circumstances. It will be 
seen by referring to Plate 2, that an opposition occurring in the latter half of the year will 
generally be more favourable {i.e., bring the two bodies closer together) than one in the first half 
of the year, and that the most favourable opposition happens when the Earth and Planet are 
situated in about 333° longitude. On the other hand, an opposition occurring in longitude 153° 
will be as unfavourable as possible. The Earth's longitude on August 26th is 333°, and on 
February 22nd it is 153° ; hence the most favourable opposition of Mars will occur on August 
26th, and the closer to that date the opposition happens the better. The most unsuitable 
oppositions are about February 22nd. 

The greatest distance at which the two planets can possibly be separated is attained 
when the Earth's longitude is 333°, and that of Mars 153° ; that is to say, when conjunction 
occurs about August 26th. 

Figures 1, 4, and 5 in the upper part of the left-hand portion of Plate 8, show the 
relative apparent sizes of the planet — at most favourable opposition (August 26th), at least 
favourable opposition (February 22nd), and at its greatest possible distance. These views 
illustrate the advantage of an opposition occurring somewhere near the end of August, when 
the appearance of the planet is to be studied. 

When the lines from the Sun to the Earth and the Sun to the Planet are at right angles, 
the Planet is said to be in quadrature. A very distinct phase is then perceptible in Mars, by 
which about a quarter of its diameter is cut off. The appearances of the planet at western and 
eastern quadrature, as shown in an inverting telescope, and the apparent size of the planet on 
the same scale as the other figures, is also given. For the topography of the planet the reader 
may refer to Plate 9. As to the times and seasons for observing Mars in its varying aspects, 
reference may be made to the Index to Planets, see page 35. 

Since the orbit of Venus lies inside that of the Earth, the appearances of this planet differ 
considerably from those of an exterior planet like Mars. It is obvious that the nearest approach 
of the two bodies will occur at inferior conjunction, or when Venus and the Earth are on the 
same side of the Sun ; and that the greatest distance between them will occur at superior 
conjunction, or when the two bodies are at opposite sides of the Sun. It might at first sight, 
therefore, be supposed that at inferior conjunction the planet would be seen best, being then 
apparently largest ; and that it would be least favourably placed at superior conjunction. The 
relative apparent sizes of this planet just before inferior, and at superior, conjunction are shown 
in the lower part of the left-hand portion of this plate ; but since in the former configuration 
the illuminated part of the globe is reduced to a Very thin crescent, and since in both cases the 
planet is enveloped in the Sun's rays, in neither of these phases is it suitably situated for 
observation. 

Venus attains its greatest brightness as an evening star about a month after its greatest 
elongation east. The greatest brightness of the same planet as a morning star precedes by 
about a month its greatest elongation west. 

The second figure has been drawn to represent the size and shape of Venus when most 
brilliant. The third figure exhibits the appearance of Venus when situated at a distance of 40° 



8 INTRODUCTION. 

from the Sun in the further part of its orbit. In this position it presents a gibbous form. 
It will be seen, however, that the diniinution of light caused by its increased distance from the 
Earth, more than compensates for the larger proportion of the illuminated surface visible, so 
that, on the whole, the amount of light received from the planet is less than when it is in the 
position coiTesponding to Figure 2. In the Index to Planets, p. 34, the method of finding the 
position of Venus for any date within the next decade is explained. 

For the general details of the planet Saturn reference may be made to Plate 11. In this 
place we discuss only the varying appearances of the rings. The right-hand portion of Plate 8 
contains twelve figures depicting the different aspects which the ringed planet presents according 
to the position it happens to occupy in its orbit. In connection with the Table of Planetary 
Phenomena, p. 33, this plate will enable the reader to determine with considerable accuracy 
the appearance of the rings at any time. If the opposition of Saturn occurs in the middle of 
January in any year, it will be found that Fig. 1 represents the system. The rings are then 
opened nearly to their full extent, and the upper portion of the ball just extends beyond the 
outer margin of the rings. If the opposition occurs in February, the rings will be found to 
have closed up somewhat, and to appear as shown in Fig. 2. If the opposition occurs in March, 
the rings will shrink almost to a straight line, as in Fig. 3. At oppositions occurring in April, 
May, and June, the appearances will be as in Figs. 4, 5, and 6, the rings appearing the more 
open the more nearly the date of opposition approaches June. Figs. 7 — 12, in a similar way. 
show the changes which this system will undergo at oppositions occurring in the latter six 
months of the year. 

It must of course be understood that the appearance here depicted for any month will not 
recur every year in that month, but will only be seen in those years in which the opposition of 
the planet occurs during the month in question, and then only with accuracy at the date of 
opposition. But as Saturn takes a period of no less than 29|- years to accomplish its revolution, 
the alteration in its appearance will vary very little for several months before and after opposi- 
tion, so that the figure for any month may be taken to represent the appearance of the system 
during the year in which opposition occurs in that month. Thus, in the year 1592 the Table 
of Planetary Phenomena tells us that the opposition of Saturn takes place in March, whence 
we learn that during this year the rings will be almost edgewise towards us. Again, in the 
year 1899 opposition occurs in June, from which we infer that during that year the rings will 
be open to their fullest extent, and most favourably situated for observations. 

These pictures have, as usual, been drawn to represent the planet as seen in an astronomi- 
cal telescope, which always inverts the object, so that Figs. 3 — 8 exhibit the appearance of the 
system when the northern face of the ring is tilted towards us so as to become visible, while 
in Figs. 1 and 2, and 9 — 12, it is the southern side of the rings which is seen. 

To facilitate reference a column has been added to the Table of Planetary Phenomena, 
p. 33, to show which of the phases are presented in the corresponding opposition. For example, 
if the opposition is in October, the column alluded to gives the number 10, which means that 
during the year in question the planet Saturn will present, when visible at all, a phase resem- 
bling that shown in Fig. 10 on Plate 8. 



Plate 9. 
CHAET OF MAES. 



This map represents the surface of Mars on the stereographic projection. It has been 
compiled (with only two exceptions, where, as shown by Mr. Knobel in 1884, the balance of 
evidence appears to incline otherwise) from Mr. X. E. Green's Chart of Mars, published in the 



INTRODUCTION. 9 

Transactions of the Royal Astronomical Society, Vol. XLIV. The details of this chart have 
been compared with views of the planet by Schiaparelli, Trouvelot, Terby, De la Rue, Lockyer, 
Knobel, Christie, Maunder, Brett, Dreyer, and others, and no form is introduced that has not 
been confirmed by the drawings of at least three observers, so that any markings to be found 
there may be taken to represent a real feature of the planet. The exceptions to which I have 
referred are called by Mr. Green — Phillips Island and Leverrier Land. The first of these 
appears to be connected by a tongue of land between Burton Bay and Dawes Forked Bay with 
Beer Continent. I have consequently changed the name to Phillips Land ; and Herschel II. 
Strait, which by the same alteration ceases to be a strait, I have called Herschel II. Inlet. 
Leverrier Land I have omitted altogether, as Mr. Knobel was unable to find any trace of it 
under very favourable circumstances in 1884. The Lassell Sea, too, of Mr. Green appears to 
be only a prolongation of Nasmyth Inlet, and the name has been accordingly omitted. 

The smaller maps at the top and bottom of the plate are also on the stereographic projec- 
tion, and represent the polar regions of the planet, showing the form and extent of the northern 
and southern snow-caps as seen by Mr. Green in 1877. 

In comparing this plate with the appearance of the planet in the telescope, it should be 
remembered that parts near the centre of the maps are by this method of projection represented 
on a smaller scale than those near the edge. For the times to observe Mars, reference may be 
made to the Index to Planets, p. 35. 



Plate 10. 
JUPITER AND COMETS. 



Owing to the absence of permanent features on Jupiter, the utmost that maps can do is to 
represent the planet in some of its ever-changing aspects. I have chosen that epoch which is 
specially interesting in connection with the remarkable red spot on Jupiter. This is shown on 
Figs. 4, 5, 7, 8, 9, 12, in the Southern (uppermost) Hemisphere of the Planet. The red spot 
was conspicuously visible for three years, the remarkable circumstance being that while it 
completed a rotation around the planet in 9 hours 55 minutes 36 seconds, there was a white 
spot in the vicinity which completed its journey in 5 or 6 minutes less. 

As to the seasons at which Jupiter may be observed with advantage, reference may be 
made to the Index to Planets, p. 36. It is there shown how the position of the planet for any 
month during the years 1892-1902 can be readily ascertained. For the System of Satellites 
surrounding Jupiter, reference may be made to Plate 6. 

The Tail of a Comet directed from the Sun. This picture is to show the relation of the 
tail of the comet to the orbit in which the body is revolving around the Sun. The direction 
of the tail is, speaking generally, governed by the law that it points from the Sun. 

Bredichirfs Theory of Comets' Tails. Three types are presented in the tails of Comets, 
as demonstrated by Bredichin. The direction of motion of the Comet is shown by the arrow- 
head on the line through the nucleus. The straightest of the three tails is most probably 
formed of Hydrogen. The tail of the second type is of a more complex character, and seems 
to be due to the presence of Hydro-Carbons in varying proportions in the body of the Comet. 
The short tails of the third type are due to Iron, or to Chlorine, or to some other similar 
element with a high atomic weight. It will of course be understood that this does not purport 
to represent the view of any actual Comet. Most Comets possess tails either of one of the 
types here shown, or sometimes a composite tail of two types. 



1 introduction. 

Plate 11. 
SATURN; 

For the study of this plate reference may be made to Plates 4, 6, 8, for various details, 
while the Index to Planets, p. 37, can be consulted for the purpose of showing when Saturn 
can be observed in the phases depicted. The lower of the three views exhibits the planet as 
shown on March 23rd, 1856. In that year the opposition took place in December, and accord- 
ingly the phase of the planet exhibited is that represented in the 12th month, that is, in Fig. 
12 on Plate 8. 

The uppermost figure shows one of those highly-interesting occasions when the ring, being 
turned edgewise, becomes almost invisible. It represents the opposition of March, 1862, so 
that throughout the year the rings presented nearly the aspect of Phase No. 3 in Plate 11. 



Plate 12. 
THE PLEIADES. 



This plate is a reproduction of a chart of the Pleiades, prepared from photographs taken 
by MM. Paul and Prosper Henry at the Paris Observatory. The photographs were exposed 
for four hours, so that stars as faint as the 17th magnitude made their impression. The picture 
shows the vast nebulosity which occupies the spaces between the principal stars of the cluster. 

The most remarkable features of this nebula are — the spiral jet projecting from the north 
preceding side of Maia, the somewhat similar but longer projection from Electra towards 
Alcyone, the barred or streaked structure of the nebula in the neighbourhood of Merope, and, 
above all, the long narrow streak running to the north of Alcyone, through Nos. 10 and 24, 
enveloping five other smaller stars in its course, and offering conclusive evidence of the physical 
connexion of the nebula with the stars forming the cluster. 

The relative positions of the brighter stars of this group have been measured with great 
accuracy by Bessel and Dr. Elkin with the heliometer, by M. Wolf with the filar micrometer, 
and by Professor Pritchard with the duplex micrometer. A comparison of the results of Bessel 
with those of Dr. Elkin, made forty-five years later, show that the relative proper motions of 
these stars, if any, is exceedingly small. This apparent fixity of the stars with regard to each 
other is often put to a practical use in the Observatory. The distance separating the various 
members of the group, as determined by these observations, may be looked upon as standard 
distances, by measuring which the equivalent in angular measure of a revolution of a micro- 
meter screw or other measuring apparatus may be ascertained. As some of my readers may 
have occasion to employ the stars for this purpose, I append a list of sixty-nine stars, with 
their places as determined by Dr. Elkin for 1886"0 (the epoch of the Chart). In the first 
column is contained Elkin's number ; in the second, the corresponding number in Bessel ; in 
the third, the magnitude as determined by Argelander in 1853 ; and in the fourth and fifth 
columns, the R. A. and Declination of the star. The numbers given in the Key Map are those 
of Bessel. 

It must, however, be borne in mind that, before using these figures for comparison with 
micrometer measures, it will be necessary to apply the corrections for Precession, Aberration, 
Nutation, and Refraction ; the methods of doing which will be found in a treatise on practical 
astronomy, such as Briinnow's " Spherical Astronomy." 



INTRODUCTION. 



11 



Positions of 69 Stars in the Pleiades for 1886*0. 



Elkin's 
No. 


Bessel's No. 


Mag. 


R.A. 1886-0. 


Declination, 


1886'0. 


1 




8-3 


54 14 


8'71 


o / 

+ 24 


45-20 


2 


... 


8'0 


18 


16-37 


24 11 


44-14 


3 


... 


9'1 


24 


20-96 


23 46 


1973 


4 


... 


8-7 


24 


42'93 


24 2 


3-70 


5 


16 g Celaeno 


6*5 


30 


23*92 


23 55 


47-80 


6 


17 b Electra 


4-7 


31 


35*58 


23 45 


14-46 


7 


• • • 


8-9 


34 


58-92 


23 54 


16-85 


8 


• • • 


8'6 


35 


2-29 


23 20 


37-74 


9 


18 m 


63 


35 


24-05 


24 28 


49-82 


10 


19 e Taygeta 


5-0 


36 


20*06 


24 6 


30-99 


11 


• • • 


8'9 


38 


6'75 


24 33 


48-97 


12 


• • • 


9-2 


38 


57*37 


24 31 


40-25 


13 


Anon. 1 


8'2 


40 


1*10 


23 40 


37-51 


14 


Anon. 2 


8*8 


41 


48-52 


24 6 


19-91 


15 


Anon. 3 


9'0 


42 


17-88 


23 43 


31-89 


16 


• • • 


9'2 


43 


25*88 


24 32 


55*13 


17 


Anon. 4 


8-1 


42 


43-59 


23 58 


40-51 


18 


Anon. 5 


91 


43 


7-37 


24 16 


10-76 


19 


Anon. 6 


9-0 


43 


39-36 


23 55 


52-09 


20 


20 c Maia 


4-8 


45 


38-91 


24 


37-85 


21 


Anon. 7 


8-2 


46 


22 39 


23 40 


54-18 


22 


21 k Asterope 


7*0 


46 


44-49 


24 11 


50-93 


23 


22 1 Asterope 


7-0 


48 


51-74 


24 10 


16-13 


24 


Anon. 8 


8*0 


51 


47-40 


23 50 


21-06 


25 


Anon. 9 


81 


52 


21-07 


23 50 


1-08 


26 


23 d Merope 


4'5 


53 


23-97 


23 35 


32-34 


27 


Anon. 10 


8-0 


55 


6-84 


23 53 


57-05 


28 


• > ■ 


8'4 


57 


15-11 


23 16 


7-00 


29 


Anon. 11 


9-1 


58 


13-42 


23 44 


52-75 


30 


Anon. 12 


7-5 


55 2 


56-99 


24 9 


5613 


31 




8-4 


3 


47-09 


24 27 


55-62 


32 


Anon. 13 


8-5 


4 


29-60 


23 38 


27-46 


33 


• • • 


9'2 


5 


46*04 


23 55 


2100 


34 


Anon. 14 


9'0 


6 


7-26 


23 25 


36-38 


35 


Anon. 15 


8*5 


7 


29-19 


23 46 


27-81 


36 


Anon. 17 


7-9 


8 


044 


23 22 


20-50 


37 


Anon. 18 


8'0 


8 


10-56 


23 47 


6-96 


38 


24 p 


8"0 


8 


36*66 


23 45 


46-97 


39 


Anon. 19 


7-5 


8 


47*95 


23 26 


5877 


40 


Anon. 20 


8'0 


9 


2'83 


24 14 


5-42 


41 


Anon. 21 


8-6 


9 


39-76 


24 18 


13-44 


42 


Anon. 22 


7'0 


9 


35-09 


23 33 


39-82 


43 


Anon. 23 


8-0 


10 


20-20 


23 19 


29-49 


44 


Anon. 24 


7'0 


10 


35 '77 


23 56 


5-89 


45 


25 n Alcyone 


3-0 


10 


37-29 


23 45 


6-] 7 


46 


Anon. 25 


8*2 


12 


49*93 


23 15 


23-17 


47 


Anon. 26 


9-0 


14 


17-05 


23 11 


25-05 


48 




7-0 


19 


28-50 


24 38 


8-98 


49 


Anon. 27 


8*5 


21 


3413 


23 58 


0-05 


50 


... 


9-2 


20 


5-54 


23 47 


24-18 


51 


Anon. 28 


7-0 


23 


58*18 


23 4 


1T76 



L2 



INTRODUCTION. 



Positions of Stars — continued. 



Elkin's 

No. 


Bessel's No. 


Mag. 


R.A. 1886-0. 


Declination, 


1886-0. 


52 


Anon. 29 


7-8 


o / 

55 25 


40-64 


o 

23 


59 


39%4 


53 


... 


9-0 


26 


57*35 


23 


49 


48*81 


54 


26 s 


7-0 


32 


37-74 


23 


30 


27-00 


55 


27 f Atlas 


4-0 


35 


45-22 


23 


42 


1390 


56 


28 h Pleione 


6'2 


36 


3-72 


23 


47 


14-31 


57 


Anon. 30 


8-4 


36 


28-30 


23 


32 


14-47 


58 


Anon. 31 


8-0 


37 


16-71 


24 


2 


48-57 


59 


Anon. 32 


7-5 


38 


31-69 


24 


1 


54-61 


60 


Anon. 33 


7'8 


39 


40-10 


23 


53 


55-51 


61 


... 


9-2 


41 


18-08 


23 


16 


47 '58 


62 


Anon. 34 


7*2 


44 


24-39 


23 


21 


49-16 


63 


Anon. 35 


9-2 


44 


41-66 


23 


53 


46'26 


64 


Anon. 36 


8-5 


46 


52-49 


23 


52 


9-15 


65 


Anon. 37 


7'9 


47 


14-34 


24 





4-27 


m 


Anon. 38 


7-5 


47 


55-89 


23 


30 


3-67 


67 


... 


9-0 


51 


49-24 


24 


19 


7-00 


68 


Anon. 39 


77 


54 


58*72 


24 


8 


53'32 


69 


Anon. 40 


73 


56 1 


24-73 


23 


36 


57-15 



Plate 13. 
ORBIT OF A BINARY STAR, 

The determination of the orbit of a Binary Star is a problem of so much interest that I 
have thought it desirable to include it in this Atlas, as the process is one of a comparatively 
simple character. 

The observations which are employed for the purpose consist of measurements of the 
distance r between the two component stars, expressed in seconds of arc, and also of the posi- 
tion angle 9 • that is to say, of the angle formed by the line joining the two stars of the pair, 
with the line from the chief of the two stars to the pole. When a sufficient number of these 
data have been accumulated by a long series of observations, then the following process, chiefly 
due to Sir John Herschel, will enable the orbit of the Binary to be ascertained. To illustrate 
the method, let us take the case of the star X Cygni, which is situated in R.A. 20 h. 43 m., 
Decl. + 36°'l, the components being 5"0 and 6'3 respectively in magnitude. 

The figures in the following table are taken from Prof. Glasenapp's paper, "Orbites des 
Etoiles Doubles du Catalogue de Poulkova," in which he investigates the orbit of this 
interesting pair. 

The first column contains a current number, the second the date of the observation, the 
third the observed position angle 0, the fourth contains the observed distance r. It should be 
remarked that when observations at widely different dates are brought together, the correction 
for precession must be attended to. 



INTRODUCTION. 



13 



No. 


Date. 


e 


r 


No. 


Date. 


9 


r 


1 


1842-66 


118°*4 


0*55 


20 


1868-66 


90°6 


0-70 


2 


43*63 


122-1 


•62 


21 


69-68 


92-6 


•62 


3 


44-91 


120*3 


•67 


22 


70-67 


89-6 


•63 


4 


4573 


115-7 


•63 


23 


71-69 


90-2 


•76 


5 


47-76 


110-2 


•62 


24 


72-61 


87-6 


•53 


6 


49'84 


109*5 


•62 


25 


73-72 


89-3 


•60 


7 


50*92 


107*7 


— 


26 


74-73 


80-5 


•67 


8 


51'90 


108-3 


•59 


27 


75-69 


88-3 


•69 


9 


52'68 


107-4 


•61 


28 


76-82 


82-5 


•68 


10 


53*85 


100-7 


•66 


29 


77-65 


84-7 


•48 


11 


54-71 


102-8 


•61 


30 


78-64 


84-6 


•61 


12 


56-83 


101-5 


•70 


31 


79-68 


82-4 


•72 


13 


57-67 


97-3 


•63 


32 


80-58 


83-8 


•83 


14 


58-59 


91-5 


•69 


33 


81-73 


80-2 


— 


15 


59-70 


97-0 


•61 


34 


82-85 


77-0 


•67 


16 


60-81 


96-5 


•72 


35 


83*73 


80-1 


•56 


17 


61-63 


92-7 


•65 


36 


86-78 


75-5 


•77 


18 


65-73 


93-9 


'45 


37 


87-83 


71-8 


•63 


19 


66'92 


91-9 


•60 


38 


88-83 


70-6 


— 



The first step in the process consists in laying down on a sheet of paper ruled into small 
squares (that generally used being known as papier millimetrique) a point for each observed 
position ; the angle 9, in degrees and decimals of a degree, being taken as an abscissa along the 
horizontal lines, and the date (t.), in years and decimals of a year, as an ordinate along the 
vertical lines. 

In Plate 13 this has been done, but on a very much smaller scale than will be found con- 
venient in practice, so as to keep all the points thus obtained within the limits of the page. 

We have then to draw among these points, by the mere judgment of the eye, and with 
a free but careful hand, a curve presenting as few and slight departures from them as possible, 
consistently " with a large and graceful sinuosity, which must be maintained at all hazards." 
It is this part of the process in which judgment and experience on the part of the computer is 
of most advantage, and no care should be spared in obtaining as good a curve as possible, since 
all the subsequent results will depend upon the skill with which it has been drawn. 

From the drawing we find the angles (a) which the tangents to this curve, at points cor- 
responding to every fifth degree of position angle, make with the horizontal lines. This angle 
may be obtained with considerable accuracy by setting a protractor so that its diameter is a tan- 
gent to the curve at the required point, and reading off the two points at which any one of the 
horizontal lines intersects its circumference. The mean of these two readings will give the 

angle a. 

We know by a property of elliptic motion that r is proportional to \/tan a. In order to 
construct the apparent ellipse, we multipl y this by some convenient factor. In the example 
before us we have taken r = 60 mm - x >/tan a. We thus obtain the following quantities :— 



14 



INTRODUCTION. 






a 


tan a 


\/tan a 


r 


o 


o 






mm. 


75 


43-3 


0-9424 


0-971 


58-3 


80 


46-7 


1-0612 


1-030 


61-8 


85 


501 


11960 


1094 


65'6 


90 


51'1 


1*2393 


1-113 


66-8 


95 


50-8 


1-2261 


1-107 


66-4 


100 


46-5 


1-0538 


1-027 


61-6 


105 


41'6 


0-8878 


942 


56-5 


110 


337 


0-6669 


0-817 


49-0 


115 


26-4 


0-4964 


0-705 


42-3 


120 


20-5 


03739 


0-611 


367 



With these values of r and 9, the points numbered from 1 to 10 in Fig. 2 are plotted down, 
S being the position of the principal component, and the line SN being taken as the zero 
of position angles. If the observations had been free from error, and the curve in Fig. 1 were per- 
fect, these points would all necessarily lie on an ellipse. As, however, the observations are more 
or less affected by error, we have to be satisfied with drawing amongst these points the ellipse 
which appears to suit them all best. This, in Fig. 2, is represented by the ellipse AEHFBK, 
and is the apparent orbit of the Satellite. 

The next step is to determine the real orbit, and with this object we first find the centre 
of the apparent ellipse. To obtain it, draw any pair of parallel chords ; the line joining 
their middle points is a diameter, the middle point of which (C) is accordingly the required 
centre of the ellipse. 

The point C is the projection of the centre of the real orbit, and S is the focus of the 

latter. Hence, A is the projection of the periastron or apse of the real ellipse near the principal 

C S 
star, and the ratio 77-7, which is unaltered by projection, is the eccentricity (e). In this case 

we find e = 0'53. 

CA 2 -CS 2 
Take SD = — ^-r — . Draw any chord EF parallel to BA. Bisect it at G. Join CG, 

and through S draw HK parallel to CG. Then will HK be bisected at S. Draw DO at right 
angles to SK, and make DL and DM each equal to SK. Join SL and SM. Then S ft, the inter- 
nal bisector of the angle LSM, is the line of nodes (or the line in which the plane of the real orbit 
intersects that of the apparent orbit), and the longitude of the node (Q) is the angle NSft 
Thus we find Q = 104° "5. The inclination (y) of the true orbit to the apparent is given by the 

equation, cos y = ow ^j . In the case before us we find cos y = 0*4761, and consequently 

61°"6. If the semi-axis-major is denoted by a, we have a = Vn" - ! — ap an( ^ smce SL + 

= 73'5 mm -, we find a = 51'03 mm - on the arbitrary scale we are using. 

The angle NSA = w = the longitude of periastron. This we find to be 256° '8. 

The angle between the line of nodes and the major axis of the real ellipse, which is usually 
denoted by X, is found from the formula, 

tan X = sec y tan (57— Q), 
from which we obtain in the case of this star X = 132°"2. 



r - 
SM 



INTRODUCTION. 15 

We have next to find P, the period ; n, the mean motion ; and e, the date of pcriastron 
passage. These are obtained by means of the following formula, in which v and u denote 
respectively the true and eccentric anomalies in the real orbit : — 

n (t - e) = u - e sin u 



tan^ = /Az« tan?L I A. 

2 V l + e 2 
tan (y + \) = sec y tan (0-Q) 

Taking t x and ^ to represent the dates 1842*66 and 1888'83 respectively — being those of the 
first and last observation — we have from the curve in Fig. 1 the corresponding values 
of 6, viz. : 123° "9, and 72° "3. Substituting these values in the third of equations A, we 
find v r = 264° '3, and v> = 174 Q, 9. Hence by means of the second equation we have u x = 
297°'0, and ii 2 = 170°'8, and substituting these values in the first we obtain 

n (1842-66 - e) = 324° -1 
n (1888-83 - e) = 166'0. 
From these two equations we find 

e = 193V27. 
and n — - 3° '426 per annum. 

360° T-* 

Also, since P = — — we obtain P = 105-1 years. 
n 

It now only remains to determine the length of the semi-axis-major in seconds of arc. 
We have already found this to be 51 '03mm. on our arbitrary scale, by calculations founded 
on the observed position angles. For the purpose of finding its length in seconds of arc, we 
must have recourse to the observed distances which, in consequence of the large errors to 
which they are liable, have been discarded in the previous steps. 

The position angle corresponding to each date of observation is read off from the inter- 
polating curve, and the distance in the apparent orbit at the corresponding position is 
measured. We thus obtain, expressed in our arbitrary scale, the series of distances corres- 
ponding to the actually observed distances. Dividing the sum of the observed distances 
(22"'38) by the sum of the corresponding computed distances (2072 mm -"22), we obtain the value, 
in seconds, of one millimetre, on the scale we have been employing, which is thus found to be 

lmra. = 0"'0108. 
Multiplying this by 51 '03, which is the value of a in millimetres, we find a = 0"'55. 

We thus have all the elements of the orbit, viz. : — 

Q - NS a = 104°-5. 

„ — x SM — SL GM>.a 

? = Cos «MTSL = 616< 
zd = NSA = 256°-8. 

\ = Tan [sec y tan (w-Q)] = 132°-2. 

t —t 
t x +t 2 _ u x + u 2 -e (sin u x + sin iu) _ j 93-7 -27 
2 2m 



n = 



e = 



P = ?60^ = 105 .j years# 
and a = 0"'55. 



16 introduction. 

Plate 14. 

NEBULA. 

These have been reproduced from the beautiful photographs obtained by Dr. Isaac 
Roberts at Maghull, near Liverpool. The picture on the right is of the great nebula in 
Andromeda, 31 M., R.A. h. 37 m., Decl. 40° 40', obtained with an exposure of 240 minutes 
with a silvered glass reflector of 20 inches aperture, on December 28th, 1889. 

The figure on the left represents the great nebula in Orion, R.A. 5 h. 30 m., Decl. S. 
5° 28'. See Mon. Notices, E.A.S., vol. xlix., p. 296. This photograph was taken at Maghull 
on the 4th February, 1889, with an exposure of 205 minutes. 

In examining photographs of nebulae, it should always be borne in mind that when the 
exposure is sufficiently long to bring out the faint details of the diffused gaseous material, it is 
necessarily too long for the brighter stars. They are accordingly over exposed, and represented 
as blots instead of the small discs that are shown on stellar photographs when suitable 
exposure has been given. The rays from the star at the top of the Orion photograph are 
due to an instrumental cause, and do not belong to the star itself. 



Plate 15. 
THE COMET OF DONATI, 1858. 



This plate represents the Comet of Donati in 1858, which was one of the most con- 
spicuous of this class of objects that has been seen in modern times. The drawing from 
which it has been taken was made by Mr. G-. P. Bond, on October 5th, 1858, at the Harvard 
College Observatory. 

Donati's comet illustrates Bredichin's doctrine on the tails of these bodies, as represented 
in Plate 10. It seems as if Donati's comet had been furnished with an elaborate hydrocarbon 
tail of type 2, and also with a hydrogen tail. The latter was in the form of a cone, and the 
edges of the cone are seen on the plate in the form of the two streamers. 



Plate 16. 
THE COMET OF COGGIA, 1874. 



The drawings of the Comet of Coggia, which appeared in 1874, were made by Mr. 
Trouvelot, at the Harvard College Observatory. The view on the left shows the aspect on 
10th June, and the other picture that on July 9th. These views exhibit a structure which 
such bodies occasionally possess. 



(17) 



CHAPTER IT— THE SOLAR MAPS. 

Plate 17. 
SOLAR PHENOMENA. 

The picture on the right is taken from a photograph by Dr. Janssen. It shows a remark- 
able sunspot, and exhibits the texture of the solar surface in the vicinity. See " Knowledge? 
February 1st, 1890. 

The picture on the left, taken from a photograph obtained at the Lick Observatory, 
represents the Solar Corona during the Total Solar Eclipse of January 1st, 1889. See " The 
Observatory? March, 1889. 

The picture below this exhibits typical forms of the prominences which project from the 
Sun's limb. A portion only of the Sun's disc is shown in the figure. 

The Monthly Maps, 39 — 50, can be used to indicate the locality of the Sun for each 
month. It lies always within the zone marked " Track of the Planets." The following list 
gives the number of the plate in which, in the corresponding month, the Sun lies at the position 
defined by the intersection of the central meridian (i.e., the line joining the south point to the 
north point on the Map) with the " Track of the Planets." 

Position of Sun. 

July ... . 

August 

September. 

Example. — In what part of the he avens is the Sun situated in August ? 

Solution.— The table just given refers to Plate 40. The central meridian cuts the track 

of the planets in Leo, in the neighbourhood of which the Sun will accordingly be 

found at the time named. 



January . . 


. 45 


April... 


... 48 


February .. 


. 46 


May ... 


... 49 


March * .. 


. 47 


June ... 


... 50 



39 


October ... 


42 


40 


November 


43 


41 


December... 


44 



Plate 18. 

PATHS OF SPOTS ACROSS THE SUN'S DISC. 

The Sun rotates around its axis, in the same direction as the Earth, in a period of 25*38 
days. In consequence of this movement the spots make their first appearance on the eastern 
limb of the disc, unless the point at which they occur happens to be turned towards the Earth 
at the time of the eruption. 



18 INTRODUCTION. 

Spots then traverse the disc parallel to the Sun's equator, are carried round the invisible 
side, and reappear, at the eastern limb, after a period of 25 38 days. Sometimes, of course, a 
spot may close up before the point of the surface at which it occurred is again turned towards 
the earth ; and, on the other hand, they frequently perform one, two, or more, complete 
revolutions. 

The axis, around which the Sun rotates, is inclined to the Ecliptic at an angle of 82° 45'. 
The inclination of the Sun's equatorial plane to the Ecliptic is therefore 7° 15'. 

The ascending node of the Sun's equator is the point at which a spot on the equator of the 
Sun would be carried by the Sun's rotation from the southern to the northern side of the 
Ecliptic, and the longitude of the node is the angle which the direction of this point makes 
with the direction of the First Point of Aries as seen from the Sun's centre. The actual value 
of the longitude of the ascending node is 74°. Its position is marked on Plate 2. 

Plate 18 shows the paths along which the spots appear to travel at different dates. They 
are here represented as actually on the face of the Sun, and not as seen through the inverting 
telescope that the astronomer ordinarily uses. 

On December 6th, the Earth is in the line of nodes, and consequently in the plane of the 
Sun's equator, and the paths pursued by the spots will therefore appear projected into straight 
lines. Again, on June 5th, when the Earth is in the opposite point of its orbit, it will be again 
in the plane of the Sun's equator, and the paths of the spots will again appear projected into 
straight lines. 

On March 4th, the Earth, being then 90° from the node, will be depressed below the Sun's 
equator by an angle of 7° 15', and the paths of the spots will appear as ellipses of considerable 
curvature, with their convexities towards the north ; while, on September 6th, from the oppo- 
site point of the orbit, the same curves will reappear, only that they will now be convex towards 
the south. From March till June, and from September till December, the curvature is de 
creasing, while in the intervening periods corresponding changes take place in the opposite 
direction. We may describe these changes in a somewhat different way by saying that, on 
June 5th and December 6th both poles of the Sun are visible just on the edge of its disc ; from 
June to December the north pole only is visible ; and from December to June the south pole 
only can be seen. 

If there were any direct method by which the Ecliptic could be determined at the telescope, 
the direction of the axis of the Sun would naturally be referred to it. It would then be found 
that on March 4th and September 6th the axis is at right angles to the plane of the Ecliptic, 
and that on June 5th and December 6th the axis makes with this plane an angle of 82° 45', 
inclining in June to the west, and in December to the east. 

Since, however, determinations of position angles are made with regard to the " parallel," 
or the direction of the apparent motion of a heavenly body (caused by the diurnal motion of 
the Earth), I have in this plate referred the position of the axis to this parallel. In each of 
the figures on the plate the point marked N is the north point of the disc, and E and W are 
the eastern and western points respectively. 

By the " position angle of the Sun's axis," is meant the angle which the projection of the 
northern half of the Sun's axis on its apparent disc makes with the meridian passing through 
the Sun's centre, reckoned positive towards the eastern, and negative towards the western 
side of the disc. If the observation is made at noon, it is the angle which the direction of the 
axis makes with the vertical, when the image is viewed projected on a sheet of paper placed 
behind the eyepiece of an inverting telescope. If the observer's back be turned towards 
the Sun, the position angle will be positive when the upper half of the axis leans towards the 
right, and negative when it leans towards the left. On such a projection the cardinal points, 



INTRODUCTION. 19 

N., S., E., W., lie just as they do in an ordinary terrestrial atlas. On January 5th and 
July 6th, the position angle of the Sun's axis is Zero j from July 6th it gradually increases in 
a positive direction until it reaches its greatest value, viz. : + 26° 20', on October 10th. From 
this date it gradually diminishes till January 5th, after which it becomes negative, reaching 
its greatest negative value, viz. - 26 Q 20', on April 5th, and returning once more to Zero on 
July 6th. 



Plates 19 to 22. 
CHARTS FOR SUN SPOT OBSERVATIONS. 

An observer who wishes to make a systematic study of the spots which appear from time 
to time on the Sun, will very soon feel the necessity for determining their positions on the 
Sun's disc, so as to thus recognise these markings when they reappear at its eastern limb, and be 
in a position to compare his observations with those of others. The latitude of a Sun spot is 
easily defined. The Sun's equator is the plane through the Sun's centre, perpendicular to the 
axis round which the Sun rotates, and the latitude of a Sun spot, north or south of the Sun's 
equator, is indicated in the same way, with regard to this plane, as the latitude of a place 
on the Earth with regard to the Earth's equator. 

We use the meridian through Greenwich as a standard from which to measure terrestrial 
longitudes east and west. To determine longitudes on a body like the Sun, we must settle 
first of all, as to what is to be the Sun's Greenwich. This is by no means easy. If there 
were any fixed object on the Sun, then of course we could take the meridian which passes 
through it, for the standard. But there is no fixed object, and we have to imagine one. At 
the moment of noon on January 1st, 1854 (which was the epoch selected by Carrington), suppose 
that a spike were driven into the Sun's equator, just at the ascending node. We reckon longi- 
tudes along the Sun's equator from the point thus defined. 

In order to facilitate observation, Plates 19 to 22 inclusive have been drawn on the prin- 
ciple employed by Mr. Arthur Thomson, by the aid of which the heliographic latitude and 
longitude of a Sun spot may be determined within a single degree. The Plates exhibit the 
appearance which the Sun would present at different times of the year if lines of longitude and 
latitude up to 40° north and south were marked on its surface. The lines radiating from the 
sides give the direction of the parallel for the dates printed on them. The position for inter- 
mediate dates can be easily interpolated by the eye. The dates at the top and bottom of the 
Maps show the periods for which each is suitable, the heading which includes the date of 
observation being always kept uppermost. It would be advisable for the observer to prepare 
a tracing from the Plate showing the parallel for the day. 

A light framework should be attached to the telescope, so as to support the plate or tracing 
at such a distance behind the eyepiece of the instrument that the image of the Sun may just 
fill the circle intended for it. The map should then be turned so as to allow a spot to travel 
along, or parallel to, the line which marks the position of the parallel on the date in question. 
Generally an equatorial telescope will have at the eyepiece a special 'line/ the image of 
which, as cast on the screen, sufficiently defines the parallel. When the image of the Sun 
exactly coincides with the circle, then read off the latitude and longitude from the map. The 
latitude is the heliographic latitude of the spot. The longitude, as read from the map, gives 
the difference in longitude between the spot and the centre of the disc. The longitude of the 
centre of the disc for noon on the 1st January of each year is given in the table on p. 20, and 



20 



INTRODUCTION. 



the amount to be subtracted from this in order to find the longitude of the centre at noon on 
any given day of the year will be found in a table on p. 21. In leap years, one day must be 
added to the date after Feb. 28. Thus, on March 1st, 1896, we take out from the table the 
quantity corresponding to March 2nd. If the observation is not made at noon, an allowance 
must be made for the change in the longitude of the centre at the rate of Q '53 per hour. 

By means of these two tables the longitude of the Sun's centre can be found at the time 
of observation. 

If the spot is to the left of the centre, its longitude is greater than that of the centre of 
the disc, in which case we add the map-reading to the longitude obtained from the tables ; if 
to the right, we subtract it. The result is the heliographic longitude of the spot referred to 
the prime meridian, which has been arbitrarily chosen as that which passed through the 
ascending node of the Equator at the beginning of the year 1854. 

Uxample. — Suppose that at 4 p.m. on the 12th August, 1893, a spot is observed in the 
position of the letter A on Plate 22. The latitude is directly read off as 24° '0 south. The 
difference of longitude between the spot and the centre is read 35° "0. The longitude of the 
centre of the disc at noon on January 1st, 1893, is 290° 9', from the table below. The quantity 
to be subtracted from this, corresponding to noon on the 12th August, is 64° 32' (see next 
page). But since the observation is made at 4 p.m., we have to increase this by 0°"55 x 4 = 2 Q 12'. 
We thus find the longitude of the centre of the disc at the time of observation to be 

290° 9' - [64° 32' + 2° 12'] = 290° 9' - 66 Q 44' = 223 Q 25' 
And since the spot is to the left of the centre, we have to add 35° '0. We accordingly find, as 
the heliographic longitude of the spot, 258° "4. 

HELIOGRAPHIC LONGITUDE OF THE CENTRE OF SUN'S DISC. 

Value of L foe each Year. 



Jan. 1. 




Greenwich 


L. 


Mean Noon. 






o / 


1892 


80 52 


3 


290 9 


4 


152 36 


5 


14 56 


6 


237 23 


7 


86 41 


8 


309 7 


9 


171 34 


1900 


34 1 


1 


256 27 


2 


118 4S 



INTRODUCTION. 



21 



HELIOGRAPHIO LONGITUDE OF THE CENTRE OF SUN'S DISC. 
Correction to L for Day of Year. 



Date. 

i 


Subtract 
from L. 


Date. 


Subtract 
from L. 


Date. 


Subt 
frorr 


ract 
L. 


Date. 


Subtract 
from L. 




o 


/ 




ft / 




o 


/ 




O / 


Jan. 1 








April 1 


105 36 


July 5 


281 


53 


Oct. 3 


31 13 


G 


65 


50 


6 


171 35 


10 


348 


3 


8 


97 11 


11 


131 


40 


11 


237 35 


15 


54 


14 


13 


163 8 


10 


197 


31 


16 


303 36 


20 


120 


23 


18 


229 5 


21 


263 


21 


21 


9 39 


25 


186 


31 


23 


295 2 


2G 


329 


10 


26 


75 43 


£0 


252 


38 


28 


58 


31 


35 





May 1 


141 48 


Aug. 4 


318 


45 


Nov. 2 


66 53 


Feb. 5 


ICO 


50 


6 


207 54 


9 


24 


52 


7 


132 48 


10 


166 


41 


11 


274 1 


14 


90 


58 


12 


198 44 


15 


232 


31 


16 


340 9 


19 


157 


3 


17 


264 39 


20 


298 


22 


21 


46 17 


24 


223 


7 


22 


330 34 


25 


4 


13 


26 


112 27 


29 


289 


10 


27 


36 27 


Mar. 2 


70 


5 


31 


178 36 


Sept. 3 


355 


13 


Dec. 2 


102 20 


7 


135 


58 


June 5 


244 46 


8 


61 


15 


7 


168 14 


12 


201 


52 


10 


310 57 


13 


127 


15 


12 


234 7 


17 


267 


46 


15 


17 8 


18 


193 


15 


17 


299 59 


22 


333 


41 


20 


83 20 


23 


259 


15 


22 


5 51 


27 


39 


38 


25 

30 


149 31 
215 41 


28 


325 


14 


27 
32 


71 42 
137 32 



(22) 



CHAPTER TIL— TEE LUNAR MAPS. 



PLACE OF THE MOON. 

From the monthly maps 39 — " 9 the positions of the Moon at different periods in the luna- 
tion can be learned. In the first place, it is to be noted thai m Satellite lies always in or 
close to that part of the sky marked as the Track of the Planets.'' When it is Ml the Moon 
is in opposition, and comes on the meridian at midnight, and hence we have the following rule : 

L : : k out the monthly map for the month in question, then the full Moon lies in that part 
of the heavens where the " Track of the Planets " crosses the central meridian, already defined 
to be the line drawn on the map from the Xorth point to the South point. 

Example 1. — In what Constellation does the full Moon appear in September 1 

Solution, — The answer is given by Plate 47, where the Track of the Planets crosses the 
central meridian in Piszes. which indicates the required position. 

ExampU -2. — When is the full Moon near the Pleiades ? 

Solution. — Plate 49 shows the Pleiades on the central meridian, and accordingly X:~rmber 
is the answer to the question. 

To find the position of the Moon at the time of the first quarter, the following is the 
method. 

L::>k out the monthly map for three months preceding the given date, then the 
constellation in or near which the Moon lies at the first quarter is shown at the intersection of 
the Track of the Planets with the central meridian. 

Example. — In what constellation does the first quarter Moon appear in June 

Solution. — The map three months earlier is Plate 41 for March. This shows the inter- 
section of the Track of the Planets and the central meridian in Virgo, which is 
accordingly the answer required. 

To find the position of the Moon at the time of the last quarter, the following is the 
method. 

Look out the monthly map for three months following the given date, then the 
Constellation in or near which the Moon lies at the last quarter is shown at the intersection of 
the Track of the Planets with the central meridian. 

Example. — In what constellation does the last quarter Moon appear in July 

Solution. — The map three months later is Plate 48, which shows that the constellation 
is Aries. 

It ought to be observed that, on account of the rapid motion of the Moon, only a rough in- 
dication of its place can be expected from the process here given, and that the accuracy will be 
greater the nearer the phase in question happens to the middle of the month. 



INTRODUCTION. 



23 



The foregoing problems cau also be solved by the more general method now to be 
described. The Table of Moon Age shows the position in the heavens which the Moon 
occupies at any age in any month. The use of this Table is as follows. 

Enter the Table in the vertical column bearing the name of the month. Then take the 
age in that column nearest the given age, and the figure at the left on the same row gives the 
number of the monthly map in which the region where the Moon is situated lies on the 
" central meridian " where the " Track of the Planets " crosses it. 



The Table of Moon Age. 



Map. 


Jan. 


Feb. 


March. 


April. 


May. 


June. 


July. 


Aug. 


Sept. 


Oct. 


Nov. 


Dec 


39 


14 


12 


10 


7 


5 


3 


29 


25 


23 


20 


18 


16 


40 


17 


14 


12 


10 


7 


5 


3 


27 


25 


23 


21 


19 


41 


19 


16 


15 


12 


10 


8 


5 


2 


28 


25 


23 


21 
24 


42 


22 


19 


17 


14 


12 


10 


8 


5 


1 





26 


43 


25 


22 


21 


16 


14 


12 


10 


7 


4 


2 


28 


26 


44 


27 


25 


23 


18 


16 


14 


11 


9 


7 
1 


4 


2 


29 


45 


29 


27 


25 


20 


18 


16 


14 


11 


9 


7 


5 


2 


46 


2 





27 


25 


21 


18 


16 


14 


11 


9 


7 


4 


47 


5 


2 


29 


27 


24 


20 


18 


16 


14 


11 


10 


7 


48 


7 


4 


3 





27 


23 


20 


18 


16 


14 


12 


9 


49 


10 


7 


5 


3 





27 


23 


20 


18 


16 


14 


11 


50 


12 


9 


8 


5 


2 





27 


23 


20 


18 


16 


14 



Example 1. — Where does the Moon lie when four days old in October ? 

Solution. — The October column in the Table of Moon Age being referred to, the sixth 
figure from the top gives 4, the age of the Moon, and the figure at the end of 
that row on the left is 44. This monthly map shows that the Moon must then 
be in or near Sagittarius. 

Example 2. — What will be the age of the Moon when on the meridian at 10 p.m. in 
August 1 

Solution. — At 10 p.m. in August, the heavens will be as in Plate 45. Therefore we 
refer to the row for Map 45 in the Table of Moon Age, which shows, under the 
column August, that the Moon must then be about 11 days old. 

Example 3. — Determine when the Moon, at the first quarter, has a specially high 
altitude. 

Solution. — The heavens must be as in Plate 49, which refers us to the last row but 
one of the Table. For the Moon to be 7 days old we look under the column 
February, in which month the heavens are as in Plate 49 about 6 p.m. 



24 



INTRODUCTION. 



Plates 23 to 3S. 



THE LUNAB OBJECTS. 

For the study of the Lunar formations, Plates 23 to 3S have been specially drawn. 
As the astronomical telescope shows 



Terminology of Lunar Quadraots. 



Moon in Inverting I.'.... y .. 



the Moon turned upside down, and with 
right and left interchanged, the maps of 
our Satellite are represented accord- 
ingly. The four quadrants (Plates 23, 
24, 25, 26) are designated in the manner 
shown in the annexed figure. For ob- 
servations of the Moon, the "terminator''' 
or boundary between light and shade. 
is the place where the objects are best 
seen, and Plates 23— 35 of the present 
Atlas have been arranged to facilitate 
observation of the Lunar formations on 
the terminator at various ages, from new 
to full. The terminators for each day 
of a lunation are marked on the quad- 
rants ; the morning terminator being 
that when the Sun is rising on the ob- 
ject in question. The quadrants also 
enable the latitudes and longitudes of 
Lunar objects to be found. 

As the Moon is so much more con- 
veniently observed from new to full, 
than from foil to new, it is the former 
series of changes that have been more 
particularly provided for. The tele- 
scopic view of the Crescent Moon, 3 days 
old, is shown in Plate 27. On the oppo- 
site page an index outline is given on 

which each of the formations receives a special number or letter. The name of the formation 
may be found by looking out the number or letter in the Catalogue of Lunar formations ; but 
for greater convenience in reference, the names of the chief objects visible in each phase are set 
out on the Index outline as well. As the Moon grows day by day, the terminator changes, and 
an ever varying series of objects are presented. A special Plate is therefore given for each day 
of the Moon's age, from the 3rd up to the 14th, when the Moon is full. Before the third day 
the Moon is so close to the Sun that observations cannot be made with advantage. 

Suppose, for instance, that the Moon is 9 days old. The observer then refers to Plate 
33. On the terminator, a little below the middle, he notes a fine crater, and desires to learn 
its name. The Index outline assigns the Number 350, and the list on the margin shows that 
this feature is named ■ Copernicus."'' The observer will be able to trace the same object with 
lessening detail up to the time of Full Moon. See Plates 34 to 38. From the comparison 
of any one of these Plates with the figure on this page, it appears that Copernicus must lie 




INTRODUCTION. 25 

in the " Second Quadrant " or on Plate 24, where the great crater will be found again as No. 380, 
a conspicuous object at 20° East longitude, and 10° North latitude. Along the top of Plate 
24 are shown the positions of the terminators at corresponding ages of the Moon. It will be 
noted that the morning terminator on the 9th day passes through Copernicus. So also does 
the evening terminator on the 24th, so that if the observer desires to study Copernicus when 
illuminated by the sunlight from the opposite side, he may repeat his observation 15 days later. 
As another illustration, let us suppose the Moon to be 4 days old, and that after com- 
paring the Moon with Plate 28 we desire to know the name of that large round dark patch, 
a little below the centre, which lies midway between the limb and the terminator. The Index 
outline shews it marked A, and from the reference to the margin or to the Catalogue the 
object is identified as the Mare Crisium. It is represented in Plate 23 as A. near the top at 
the left. 

To show the mode of representing the ranges of Lunar mountains, we may suppose the stu- 
dent to be looking at the Moon a little after the first quarter, say on the eighth day, as on Plate 
32. He notices a remarkable formation a little below the centre. The Index outline labels 
this object c, and the margin shows that we are looking at the lunar Apennines. Plate 24 
exhibits the Apennines pointing towards Copernicus. 

Suppose that a view of some particular formation of known name be specially desired, the 
process is as follows. Look it out in the Index at the end of this volume, the first reference 
is to the quadrant, and the next is to the plate where the object is represented on the 
terminator. 

Thus, for instance, to find the position of Plato. The Index shows first of all that it lies 
on Plate 24, that is, in the Second Quadrant. The next reference is to Plate 32, which shows 
the object lying near the terminator when the Moon is 8 days old. There are further references 
to 33, 34, and 35, where the object is also visible. The evening terminator on Plate 24 shows 
that when this object is suitably placed for observations with the opposite illumination, the 
Moon is about 23 days old. The subsequent references in the Index are to those pages of the 
Introduction in which the object is mentioned. 

The beginner should, however, be apprized that even with the assistance which it is hoped 
that these maps will afford him, considerable pains are often required to identify the lunar 
objects. In the first place, the position of the Moon shifts slightly, thus producing what is 
called libration. It therefore follows that the hemisphere turned towards us varies somewhat. 
The maps are accommodated to a state of mean libration, and the student must not be 
surprised if he finds an object sometimes higher and sometimes lower than its position in the 
map would have led him to expect. These changes often produce considerable variations in the 
appearance of the lunar formations. It must also be .remembered that the age of the Moon 
cannot be always exactly that of the map which comes nearest to it. This will often involve 
considerable alterations in the appearance of the lunar formations from those which they present 
at the exact phase which the map depicts. The elucidation of the several points which thus 
arise will afford much interesting occupation, and will, it is hoped, lead the student to a close 
acquaintance with the beautiful scenery of our Satellite. 



26 



INTRODUCTION. 



CATALOGUE OF LUNAR OBJECTS. 



Figures refer to the Number of the Crater or similar formation, capital letters refer to the so-called" Seas," and 
small letters refer to the Mountain Ranges and isolated Mountains. 



1 Langrenus. 

2 Kastner. 

3 Vendelinus. 

4 Maclaurin. 

5 Hecataeus. 

6 Ansgarius. 

7 Petavius. 

8 Wrottesley. 

9 Palitzch. 

10 Hase. 

11 Legendre. 

12 W. Humboldt. 

13 Phillips. 

14 Furnerius. 

15 Stevinus. 

16 Snellius. 

17 Adams, 

18 Marinus. 

19 Fraunhofer. 

20 Oken. 

21 Vega. 

22 Pontecoulant. 

23 Biela. 

24 Hagecius. 

25 Boussingault. 

26 Boguslawsky. 

27 Schomberger. 

28 Webb. 

29 Messier. 

30 Lubbock. 

31 Godenius. 

32 Guttemberg. 

33 Magelhaens. 

34 Colombo. 

35 Cook. 

36 Santbech. 

37 McClure. 

38 Crozier. 

39 Bellot. 

40 Borda. 

41 Reichenbach. 

42 Rheita. 

43 Neander. 

44 Metius. 

45 Fabricius. 

46 Janssen. 



47 Steinheil. 

48 Vlacq. 

49 Rosenberger. 

50 Nearchus. 

51 Hommel. 

52 Pitiscus. 

53 Mutus. 

54 Manzinus. 

55 Censorinus. 

56 Torricelli. 

57 Capella. 

58 Isidorus. 

59 Madler. 

60 Bohnenberger. 

61 Rosse. 

62 Fracastorius. 

63 Piccolomini. 

64 Stiborius. 

65 Riccius. 

66 Rabbi Levi. 

67 Zagut. 

68 Lindenau. 

69 Nicolai. 

70 Biisching. 

71 Buch. 

72 Hypatia. 

73 Delambre. 

74 Theon Senr. 

75 Theon Jurir. 

76 Taylor. 

77 Alfraganus. 

78 Kant. 

79 Theophilus. 

80 Cyrillus. 

81 Catharina. 

82 Tacitus. 

83 Beaumont. 

84 Descartes. 

85 Abulfeda. 

86 Almanon. 

87 Geber. 

88 Abenezra. 

89 Azophi. 

90 Sacrobosco. 

91 Fermat. 

92 Polybius. 



93 Pons. 

94 Pontanus. 

95 Gemma Frisius. 

96 Poisson. 

97 Aliacensis. 

98 Werner. 

99 Apianus. 

100 Playfair. 

101 Blanchinus. 

102 La Caille. 

103 Delaunay. 

104 Faye. 

105 Donati. 

106 Airy. 

107 Argelander. 

108 Parrot. 

109 Albategnius. 

110 Hipparchus. 

111 Halley. 

112 Hind. 

113 Horrocks. 

114 Rhceticus. 

115 Reaumur. 

116 Walter. 

117 Nonius. 

118 Fernelius. 

119 S toner. 

120 Faraday. 

121 Maurolycus. 

122 Barocius. 

123 Clairaut. 

124 Licetus. 

125 Cuvier. 

126 Bacon. 

127 Jacobi. 

128 Lilius. 

129 Zach. 

130 Kinau. 

131 Pentland. 

132 Curtius. 

133 Simpelius. 

134 Miller. 

135 Schubert, 

136 Apollonius. 

137 Firmicus. 

138 Azout. 



INTRODUCTION. 



27 



CATALOGUE OF LUNAR OBJECTS— continued. 



139 Neper. 

140 Condorcet. 

141 Behaim. 

142 Lapeyrouse. 

143 Hanno. 

144 Le Gentil 

145 Tannerus. 

146 Huggins. 

147 Timoleon. 

148 Zeno. 

149 Schwabe. 

150 Hansen. 

151 Alhazen. 

152 Picard. 

153 Pierce. 

154 Taruntius. 

155 Secchi. 

156 Proclus. 

157 Maskelyne. 

158 Jansen. 

159 Vitruvius. 

160 Maraldi. 

161 Cauchy. 

162 Emmart. 

163 Oriani. 

164 Plutarch. 

165 Seneca. 

166 Macro-bins. 

167 Cleomedes. 

168 Tralles. 

169 Burckhardt. 

170 Hahn. 

171 Berosus. 

172 Gauss. 

173 Geminus. 

174 Bernouilli. 

175 Messala. 

176 Berzelius. 

177 Hooke. 

178 Schumacher. 

179 Struve. 

180 Mercurius. 

181 Franklin. 

182 Cepheus. 

183 Oersted. 

184 Shuckburgh. 

185 Chevallier. 

186 Atlas. 

187 Hercules. 

188 Endymion. 



189 De la Rue. 

190 Strabo. 

191 Thales. 

192 Gartner. 

193 Democritus. 

194 Arnold. 

195 Moigno. 

196 Peters. 

197 Meton. 

198 Euctemon. 

199 Challis. 

200 Main. 

201 Gioja. 

202 Scoresby. 

203 Barrow. 

204 W. C. Bond. 

205 Christian Mayer. 

206 Archytas. 

207 Aristoteles. 

208 Eudoxus. 

209 Alexander. 

210 Egede. 

211 Great Alpine Valley. 

212 Grove. 

213 Mason. 

214 Plana. 

215 Burg. 

216 Baily. 

217 Daniell. 

218 Posidonius. 

219 Chacornac. 

220 Le Monnier. 

221 Bonier. 

222 Bond. 

223 Maury. 

224 Littrow. 

225 Newcomb. 

226 Dawes. 

227 Plinius. 

228 Ross. 

229 Maclear. 

230 Sosigenes. 

231 Julius Csesar. 

232 Boscovich. 

233 Taquet. 

234 Menelaus. 

235 Sulpicius Gallus. 

236 Bessel. 

237 Linne. 

238 Aratus. 



239 Conon. 

240 Manilius. 

241 Ukert. 

242 Triesnecker. 

243 Hyginus. 

244 Agrippa. 

245 Godin. 

246 Ritter. 

247 Sabine. 

248 Dionysius. 

249 Manners. 

250 Arago. 

251 Ariadseus. 

252 Silberschlag. 

253 De Morgan. 

254 Cayley. 

255 Whewell. 

256 Calippus. 

257 Thesetetus. 

258 Cassini. 

259 Aristillus. 

260 Autolycus. 

261 Mosting. 

262 Lalande. 

263 W. Herschel. 

264 Ptolemaeus. 

265 Alphonsus. 

266 Arzachel. 

267 Alpetragius. 

268 Lassell. 

269 Davy. 

270 Guerike. 

271 Parry. 

272 Bonpland. 

273 Fra Mauro. 

274 Thebit. 

275 Straight Wall. 

276 Birt. 

277 Purbach. 

278 Regiomontanus. 

279 Hell. 

280 Pitatus. 

281 Hesiodus. 

282 Gauricus. 

283 Wurzelbauer. 

284 Sasserides. 

285 Ball. 

286 Lexell. 

287 Nasireddin. 

288 Orontius. 



28 



INTRODUCTION. 



CATALOGUE OF LUNAR OBJECTS— continued. 



289 Picfcet. 

290 Saussure. 

291 Tycho. 

292 Heinsius. 

293 Wilhelm I. 

294 Longomontanus. 

295 Street. 

296 Maginus. 

297 Deluc. 

298 Clavius. 

299 Cysatus. 

300 Moretus. 

301 Short. 

302 Newton. 

303 Gruemberger. 

304 Cabeus. 

305 Casatus. 

306 Klaproth. 

307 Wilson. 

308 Kircher. 

309 Bettinus. 

310 Zuchius. 

311 Segner. 

312 Blancanus. 

313 Scheiner. 

314 WeigeL 

315 Host, 

316 Bailly. 

317 Schiller. 

318 Bayer. 

319 Pingre. 

320 Hansen. 

321 Phocylides. 

322 Wargentiu. 

323 Schickard. 

324 Drebbel. 

325 Inghirami. 

326 Hainzel. 

327 Lehmann. 

328 Lacroix. 

329 Piazzi. 

330 Lagrange. 

331 Fourier. 

332 Yieta. 

333 Doppehnayer. 

334 Lee. 

335 Vitello. 

336 Clausius. 

337 Capuanus. 

338 Cichus. 



339 Mercator. 

340 Campanus. 

341 Kies. 

342 Bullialdus. 

343 Lubiniezky. 

344 Nicollet. 

345 Hippalus. 

346 Agatharcbides. 

347 Gassendi. 

348 Herigonins. 

349 Letronne. 

350 Mersenius. 

351 Cavendish. 

352 Byrgius. 

353 Eichstadt. 

354 De Yico. 

355 Ramsden. 

356 Billy. 

357 Hansteen. 

358 Sirsalis. 

359 Fontana. 

360 Zupus. 

361 Criiger. 

362 Rocca. 

363 Grimaldi. 

364 Damoiseau. 

365 Riccioli. 

366 Lohi'niaun. 

367 Hermann. 

368 Flamsteed. 

369 Wichmann. 

370 Euclides. 

371 Landsberg. 

372 Gambart. 

373 Soinmering. 

374 Schroter. 

375 Pallas. 

376 Bode. 

377 Reinhold. 

378 Hortensius. 

379 Milichius. 
3S0 Copernicus. 

381 Stadius. 

382 Eratosthenes. 

383 Gay Lussac. 

384 Tobias Mayer. 

385 Kunowsky. 

386 Encke. 

387 Kepler. 
3SS Bessarion 



389 Reiner. 

390 Marius. 

391 Hevel. 

392 Cavalerius. 

393 Olbers. 

394 Cardanus. 

395 Krafft. 

396 Yasco de Gama. 

397 Seleucus. 

398 Marco Polo. 

399 Archimedes. 

400 Beer. 

401 Timocharis. 

402 Lambert. 

403 Pytheas. 

404 Euler. 

405 Diophantus. 

406 Delisle. 

407 Caroline Herschel. 

408 Carlini. 

409 Leverrier. 

410 Helicon. 

411 Kirch. 

412 Piazzi Smyth. 

413 Plato. 

414 Tima?us. 

415 Birmingham. 

416 Epigenes. 

417 Goldschmidt. 

418 Anaxagoras. 

419 Fontenelle. 

420 Philolaus. 

421 Anaximenes. 

422 J. J. Cassini. 

423 Condamine. 

424 Maupertuis. 

425 Bianchini. 

426 Sharp. 

427 Mairan. 

428 Foucault. 

429 Harpalus. 

430 J. F. W. Herschel. 

431 Anaximander. 

432 Pythagoras. 

433 South. 

434 Babbage. 

435 (Enopides. 

436 Robinson. 

437 Cleostratns. 

438 Xenophanes. 



INTRODUCTION. 



29 



CATALOGUE OF LUNAR OBJECTS— continued. 



439 Repsold. 

440 Harding. 

441 Gerard. 

442 Lavoisier. 

443 Ulugh Beigh. 

444 Lichtenberg. 



445 Briggs. 

446 Otto Struve. 

447 Aristarchus. 

448 Herodotus. 

449 Wollaston. 

450 Schiaparelli. 



451 Gruithuisen. 

452 Brayley. 

453 Galileo. 

454 Horrebow. 



MOUNTAIN RANGES AND ISOLATED MOUNTAINS. 



a 
b 
c 
d 
e 
f 

g 
h 



Alps. 

Caucasus. 

Apennines. 

Carpathians. 

Sinus Iridum Highlands. 

Haemus. 

Pyrenees. 

Altai. 

Riphsean Mountains. 

Lahire. 

Taurus. 

Teneriffe Range. 



m Straight Range. 

n Percy Mountains. 

o Harbinger Mountains. 

p Hercynian Mountains. 

q Pico. 

r Piton. 

s Mt. Argseus. 

t Mt. Hadley. 

u Laplace Promontory. 

v Mt. Huygens. 

to Mt. Bradley. 



Mountains near the Limb : — 
D'Alembert Mts.— on the east limb, extending from S. lat. 19° to N. lat. 12°. 
The Cordilleras — near the east limb, extending from S. lat. 23° to S. lat. 8°. 
The Rook Mountains— on the east limb, extending from S. lat. 39 Q to S. lat. 16°. 
The Doerfel Mountains — on the south-east limb, extending from S. lat. 80° to S. lat. 57 Q . 
The Leibnitz Mountains extend from S. lat. 70° on the west limb to S. lat. 80° on the 

east limb. 
Humboldt Mountains— on the west limb, extending from N. lat. 72° to N. lat. 53°. 



MARIA or SEAS. 



A Mare Crisium. 

B „ Foecunditatis. 

C „ Australe. 

D „ Humboldtianum. 

E „ Tranquillitatis. 

F „ Nectaris. 

G Lacus Somniorum. 

H „ Mortis. 

J Mare Serenitatis. 

K „ Frigoris. 

L „ Imbrium. 

M „ Vaporum. 



N 


Sinus iEstuum. 


P 


„ Medii. 


Q 


Mare Nubium. 


R 


Sinus Iridum. 


S 


Oceanus Procellarum 


T 


Mare Humorum. 


V 


Palus Somnii. 


W 


Sinus Roris. 


X 


Palus Nebularum. 


Y 


Mare Smythii. 


Z 


Palus Putredinis. 



(30) 



CHAPTER IV.— THE MOSTHLY MAPS. 



Plates 39—50. 

The diurnal rotation of the earth gives rise to an apparent revolution of the celestial 
sphere in a period of one sidereal day. In consequence of this movement the appearance of 
the sky is continually changing, so that to the beginner it is often a matter of considerable 
difficulty to know where to look for any particular star or constellation. 

A a :he sidereal day is about 4 minutes shorter than the ordinary mean solar day, the effect 
produced is a gradual shifting of the stars from east to west. — a star which occupies a certain 
position one night, reaches the same position 4 minutes earlier the next night, so that at the 
end of a month this position is attained 2 hours earlier than at the beginning. 

In order to render these changes easier to follow, and to enable the student to identify 
the principal constellations without difficulty, and to know where any particular star or 
group of stars is to be found at any time, Plates 39 — 50 are used. They represent the positions 
of the principal stars down to the 4th magnitude at intervals of 2 sidereal hours. The first 
shows the aspect of the heavens at midnight on January 15th, the sidereal time then being 7h. 
37m. This map will also represent the appearance of the visible hemisphere at the times 
shown in the corners at the top. Thus we find that the first of the monthly maps may be used 
in February at 10 p.m., in March at S p.il From April to September inclusive, the stars will 
occupy the positions here indicated during the daylight hours, when they will be invisible ; but 
in October this aspect of the sky may again be seen at 6 a.il, in November at 4 a.il, and in 
December at 2 A.M. To find the right map for any month and hour we can make use of the 
following Table. 

TABLE TO FIND THE ASPECT OF THE HEAVENS AT ANY GIVEN 
MONTH AND HOUE OF NIGHT. 













Mid- 












P.X. 


P.M. 


P.X. 


P.M. 


nisrht. 


A.X. 


A.X. 


A.X. 


A.X. 




-fch. 


- 


ih 


10h- 


llh. 


9l 


4h. 


Eh. 


Sh. 


January 


--- 


48 


49 


50 


c> 


40 


41 


42 


43 


February . . 




49 


50 


39 


40 


41 


49 


43 




March 




50 


39 


40 


41 


4: 


43 


44 




April 






40 


41 


4S 


43 


41 






May 






41 


19 


43 


44 


45 












--■: 


43 


14 


45 


46 






July 






43 

44 


44 
45 


45 

46 


4-: 
-r 


47 
48 








September. 




44 


45 


46 


47 


48 


49 


50 








IS 


-.-. 


47 


48 


-/: 


:■: 


39 




1 " : Tember.. 


4£ 


46 


47 


if 


49 


50 


39 


40 


41 


December. . 


46 


47 


48 


JL'.i 




:: 


40 


41 


.- 



introduction. 31 

Examples of the Use of this Table : 

I. To find the map suitable for 10 p.m. in March. Take the third row, and under 10 p.m. 

is found 40. This means Plate 40. 

II. What map should be used at 7-30 p.m. in November ? On the eleventh row we find 

47 under 8 p.m., and as 7-30 is nearer to 8 than to 6, we accordingly choose Plate 47. 

It will of course be understood that the maps have been designed to represent the appear- 
ance of the sky on the 15th of each month, at the hours mentioned. The changes are, however, 
so slow, that for most purposes they will be found sufficiently applicable to the whole month. 
If, however, greater precision is desired, it can be obtained by subtracting half-an-hour from 
the time given on the map for each week after, or adding half-an-hour for each week before 
the middle of the month. Plate 39 is thus quite accurate at 11 p.m. on the 30th of January, 
or at 8-30 p.m. on March 8th ; similarly Plate 41 is correct at 5 a.m. on the 30th December, or 
at 11 p.m. on the 1st April. 

These maps have been constructed for the latitude 53° 23' N. They will thus be suitable 
for all parts of the British Isles. The bounding circle represents the horizon, and the small 
cross at the centre marks the position of the zenith. The projection used is such that the 
distance of each star from the centre of the map is proportional to the star's zenith distance. 
The angle which the line joining a star to the zenith makes with the central meridian is the 
azimuth of the star. 

As the celestial sphere is viewed from the inside, the cardinal points are not disposed on 
these maps as in a terrestrial atlas. In the present case, when the north is at the top, the west 
will be on the right, and the east on the left. 

If we wish to compare any region of the sky with the map, we suppose a radius drawn 
through the middle of this region, and the point where it cuts the circumference of the 
map gives us the azimuth. Turning our face towards this point of the compass, we hold 
the map so that the corresponding point of the circumference is lowest, and, remembering 
that the centre of the circle represents the zenith, we have on the map a picture of the corres- 
ponding position of the sky. For instance, if we wish to find the constellation Leo at midnight, 
in the middle of March, we find from Map 41 that the radius drawn through the middle of it 
cuts the circumference at about fths of the way from south towards west. We accordingly turn 
to that point of the horizon, and we can readily find this constellation. The brightest star, 
Kegulus, will be then almost exactly half-way between the zenith and horizon, or at an altitude 
of 45°, while the " Sickle," which forms the fore-part of this constellation, will be found tilted 
over towards the west. If we turn a little further towards the west, we shall find the two 
bright stars, Castor and Pollux, a little lower in the sky, the line joining them being nearly 
horizontal. Again, if in October, at 10 p.m., we wish to examine " The Plough," as the group 
formed by the principal stars in Ursa Major are called, we go to Plate 47 and find this group 
almost clue north. We have accordingly to turn the map upside down, so as to bring the north 
point lowest, and we then see this figure stretching across the sky in a horizontal direction, at 
an altitude of about 20°. If we turn to the north-east, we again find Castor and Pollux just 
above the horizon, but this time the line joining them is very nearly vertical. 

The names of the constellations have been printed on the maps, so that when the maps 
are held in the proper position for any constellation its name may be erect. 

As the student becomes more familiar with the stars, he will probably wish to identify 
many fainter groups that do not appear on these plates. In order to enable this to be done 



32 introduction. 

with facility, the faint dotted lines have "been inserted which mark the "boundaries of the regions 
which each of the plates, 51 — 70, of the general Atlas, coyer on the sky. These lines appear 
everywhere in pairs, the spaces between the pairs "being the areas by which the maps overlap 
each other. The numbers within the regions thns marked out are those of the corresponding 
plates in this volume, where more detailed maps of the same part of the sky will be found. 
Thus in Plate 40 we find the constellation Leo almost wholly contained in the spaee corres- 
ponding to Plate 60, and some of its principal stars in the space common to Plates 54, 55, and 
60. If we turn to Plate 60 we shall find the whole group on a much larger scale, while 54 
and 55 show the more northern parts of this constella:. : ~_ 



(33) 



CHAPTER V.— THE INDEX TO THE PLANETS. 

It is a special object of this work to facilitate observation of the principal planets. 
Let it be once for all understood that those who want exact positions must seek elsewhere for 
them. What is here given is only an index to the planets generally, sufficient for the following 
purposes : — 

(1) To find the position on the heavens which each principal planet occupies. 

(2) To find when any principal planet rises or souths or sets. 

(3) To determine the best season during any year for the observation of any principal 

planet. 

(4) To ascertain the name of any principal planet when the time and place of its appear- 

ance are known. 
The foundation of the Index to Planets, up to a.d. 1902, is given in the following table, 
which contains the " Planetary Phenomena " as described at the head of each column. 



PLANETARY PHENOMENA. 



1 


2 


3 


4 


5 


6 


7 


8 




A.D. 


Mercury, 

Evening 

Star. 


Mercury, 

Morning 

Star. 


Venus, 

Evening 

Star. 

Greatest 

Elongation 

E. 


Venus, 
Morning 

Star. 

Greatest 

Elongation 

W. 


Mars 
in 

Opposition. 


Jupiter 
in 

Opposition. 


Saturn 
in Oppo- 
sition. 


Sri 00 

si £ ® 

•■4-1 &> 

O o <D 

25 co 


1892 
1893 
1894 

1895 
1893 
1897 
1898 
1899 

1900 
1901 
1902 


Mar. 27— Apr. 3 

Mar. 11-18 
Feb. 23— Mar. 2 

Feb. 6-13 

Jan. 19-26 

Apr. 25— May 2 

Apr. 8-15 
Mar. 22-29 

Mar. 5-12 

Feb. 16-23 

Jan. 30— Feb. 6 


Sept. 7-14 
Aug. 23-30 
Aug. 6-13 

Nov. 7-14 
Oct. 22-29 
Oct. 5-12 
Sept. 18-25 
Sept. 2-9 

Aug. 16-23 
July 29 — Aug. 5 
Oct. 31— Nov. 7 


April 
December 

July 

February 
September 

April 
December 


September 

April 
November 

July 
February 
September 

April 


August 
October 

December 

January 

February 


October 
November 
December 

January 
February 

March 

April 

May 
June 
August 


March 

March 
April 

April 
May 
May 
May 
June 

June 
July 

July 


3 
3 
4 

4 
5 
5 
5 
6 

6 

7 
7 



MERCURY. 

The first column of the Table of Planetary Phenomena gives the year a.d.; the 2nd 
column gives a period of a week during the early months of the year, when Mercury may be 
looked for as an Evening Star, low in the west, soon after sunset. The 3rd column gives a 



D 



34 



INTRODUCTION. 



period of a week in Autumn, when Mercury may be looked for as a Morning Star, low down in 
the east, before sunrise. There are, of course, other times when this planet may be observed, 
but in the present work it is not necessary to give further information. 

VENUS. 

The 4th column of the Table of Planetary Phenomena gives the month in which Venus 
attains the greatest elongation East, i.e., is at the greatest apparent distance east from the Sun. 
As already stated, p. 7, this planet attains its greatest brilliancy as an Evening Star in about 
a month, or rather longer, after reaching the phase mentioned. For example : — In the year 
1895, it appears that Venus will have its greatest elongation east in July, and the planet is 
brightest as an Evening Star about August. 

The 5th column of the Table of Planetary Phenomena gives the month in which Venus 
has the greatest elongation west. It attains its greatest brilliancy as a Morning Star about a 
month, or rather more, before the phase now mentioned is attained. For example : — In the 
year 1900, Venus attains its greatest elongation west in September, and the planet^is brightest 
as a Morning Star in August of that year. 



IXDEX TO VEXUS. 



A.D. 


Jan. 


Feb. 


Mar. 


April . 


3 lay. 


Juue. 
39 


July. 
39 


Aug. 


Sept. 


Oct. 


Nov. 


Dec. 


1S92 


46 


47 


48 


49 


39 


39 


40 


41 


42 


43 


1393 


44 


46 
46 


47 


48 


49 


50 


40 


41 


42 
40 


43 


45 


46 


1894 


46 


43 


47 


4S 


49 


50 


39 


42 


43 


44 


1895 


45 


47 


4S 


49 


50 


40 


41 


41 


41 


41 


41 


42 


1896 


44 


45 


46 


47 


49 


50 


39 


40 


42 


43 


44 


45 


1S97 


47 


48 


48 


49 


4S 


49 


49 


39 


40 


41 


42 


43 


1S9S 


45 


43 


47 


49 


50 


40 


41 


42 


43 


43 


43 


43 


1S99 


44 


45 


46 


47 


4S 


49 


50 


40 


41 


42 


44 


45 


1900 


46 


47 


49 


50 


50 


50 


50 


39 


40 


41 


42 


43 


1901 


44 


46 


47 


48 


49 


39 


40 


41 


42 


43 


45 


46 


1902 


46 


46 


46 


47 


4S 


49 


50 


39 


40 


41 


43 


44 



The Index to Venus, by which title we have designated the preceding table, enables the 
position of the planet to be readily ascertained for any month up to the end of 1902. It must 
be remembered that, as the unit of time adopted in this index, as well as in those of the other 
planets, is a month, and as the locality can only be indicated by dividing the Track of the 
Planets around the heavens into twelve portions, no close precision need be looked for. Xo 
doubt in the great majority of cases the map named in the index will be that where the central 
meridian lies nearest the planet. In other words, the place of the planet is given to within an 
hour. It may, however, happen m extreme conditions that the map indicated is not the best 
one, but in such cases the right map always lies next to that to which the index refers. Even 
when this happens, the purposes of the index are not frustrated, for the planet will he so near 
to the position in question, that its identification will be unmistakable, unless on the rare occa- 
sions when two planets happen to lie close together. 



INTRODUCTION. 



35 



At the top of the " Index to Venus " the names of the months are given in a horizontal 
row. The vertical column on the left gives the year a.d. The index shows a certain 
number corresponding to each month and year ; this number refers to one of the monthly maps. 
The planet lies at the region, on this map, where the central meridian cuts the " Track of the 
Planets." The use of the index is extremely simple, and we proceed to illustrate it by a few 
examples. 

Examples to Illustrate the Use of the Index to Venus. 

Example 1.— Where is the planet Venus situated in October, 1893 1 
Solution.— -The "index to Venus "for the month of October in the year 1893, refers 
to Map 43. The central meridian cuts the Track of the Planets between Libra 
and Scorpio, that is accordingly the position of Venus ; and a comparison with 
Map 45 shows that this portion of the heavens sets at 6 p.m. in October, so that 
the planet will probably not be seen. 

Example 2. — Where does Venus lie in June, 1894 1 

Solution— -The index refers to Plate 49. The " Track of the Planets " cuts the central 

meridian close to the Pleiades, so that Venus is in that vicinity at the time named -, 

and since Map 41 shows that the Pleiades set during the daylight hours in June, 

it will be useless to look for the planet at this time. 
Example 3. — Where will Venus lie at greatest elongation East in 1897 % 
Solution.— -The phase named is attained in February, the Index refers to Map 48, 

whence the position of the planet is near Aries. 

MARS. 

We have already explained the different appearances presented by Mars in connection with 
Plate 8. We are now to illustrate the use of the Index to Mars, by which the position of the 
planet at all dates up to a.d. 1902 can be determined with sufficient approximation. The 
structure of the index is on the same principle as that of the index to Venus, and its use will 
be shown by examples. 

INDEX TO MARS. 



A.D. 


Jan. 


Feb. 


Mar. 

44 

49 

45 
48 
44 


April. 


May. 


June. 

46 
39 


July. 


Aug. 


Sept. 


Oct. 


Nov. 


Dec. 


1892 
1893 


43 

48 


44 

48 


45 

50 


45 
50 


46 
40 


46 

40 


46 
41 


46 
41 


46 
42 


47 
43 


1894 
1895 
1896 


43 

48 
43 


44 
48 
44 


46 
49 

45 


46 

50 
46 


47 

50 

47 


48 
39 

47 


48 
40 

48 


48 
40 
49 


48 
41 
49 


48 
42 
50 


48 
42 
50 


1897 
1898 
1899 


50 
45 
39 


50 
46 

39 


50 
46 
39 


39 

47 
39 


39 

48 
40 


40 
49 
40 


41 
49 
41 


41 

50 
42 


42 

39 
42 


42 
39 
43 


43 
40 
44 


44 
40 
44 

41 
45 
41 


1900 
1901 
1902 


45 
41 
46 


46 
40 
46 


47 
40 

47 


48 
40 
48 


48 
40 
49 


49 
41 
49 


50 
41 

50 


39 

42 
39 


39 
43 

40 


40 
43 

40 


40 
44 
41 



36 



INTRODUCTION. 



Examples to Illustrate the Use : f the Index to Maes. 

Example 1. — Find the place of Mars in February, 1S94. 

: :lution. — The index shows Plate 44. This locates Mars in S gHfarioa or Scorpio, 
and the planet comes on the meridian in daylight. 

Example 2. — When is Mars on the meridian in January. l£ I ; 

5 : 'ution. — The index refers to Plate 45, which shows that Mars is in Sagittarius, 
and the Table in the left-hand corner of the Plate shows that in January this 
constellation souths at noom It may be remarket:! that, when twelve or thirteen 
months from opposition. Mars always culminates about noon. 

Example 3. — Where is Mars situated in the opposition of 1S96 ! 
5 .lUion. — The Table of Planetary Phenomena shows the opposition to be in Decem- 
ber. The Index refers to Map 50, so the planet is situated over Orion. 

JUPITER 

The great planet moves over the heavens so that the oppositions usually succeed each 
other at intervals of 13 morths. The Index to Jupiter is arranged in the same maimer as 
those of Tenus and Mars. 



rSDEX TO JTPITEE. 



a.d. Jan. I r 


Mar. 


ApriL May. Jane. July. 


Aug. Sept. I Oct. 


Nov. 


Dec. 


1893 1? 

:- is 


49 


4 


18 

49 


45 
49 


43 
49 


1894 

IS ' 


5 
39 


49 
50 
39 


50 

39 


49 


IS 

39 


39 


50 
39 
If 


50 
39 

40 


90 50 

39 39 
H 40 


50 
39 
40 


50 
39 
40 


1892 40 

1893 4L 
1892 


4: 

41 
42 


40 
41 
42 


M 

41 
42 


1 

41 
42 


40 
41 
42 


40 
41 
13 


41 . 41 

41 42 42 

42 42 43 


41 
12 

43 


41 
42 
43 


1901 

1902 


43 
44 
45 


43 
44 
45 


43 

44 

45 


44 
45 


13 

44 
45 


43 
44 

IS 


43 
44 


43 43 43 

44 44 44 
46 46 46 


44 
44 
46 


44 
45 
46 



Examples to Illustrate the Use of the Ixdex to Jupiter. 

Example 1. — When will Jupiter be in opposition in the year 1900, and in what part 
of the heavens will the planet then Ke 

Solution. — The Table of Planetary Phenomena, column 7, shows that Jupiter will be 
in oppositi >n in M y 1901 The ' ; Index to Jupiter" for this date gives Plate 
43. which shows that Jupiter will then be about Scorpio or Libra : and since 
Map 41 shows this part of the sky on the eastern and Map 45 shows it on the 
western horizon, it follows that the planet may be seen from about 8 p.m. till 
4 a.m. during the given month. 



INTRODUCTION. 



37 



Example 2. — At what oppositions will Jupiter rise highest in the heavens at culmi- 
nation 1 

Solution. — Plates 39 — 50 show that the most northern part of the " Track of the 
Planets " lies a little to the west of Gemini, and that it is on the meridian in 
December at midnight. A planet in opposition crosses the meridian at midnight. 
Hence Jupiter will be highest when opposition occurs in December, as, for 
example, in 1894. 

Example 3. — About what time does Jupiter rise in March, 1899 ? 

Solution. — The Index refers to Map 42, showing that the planet is in Virgo, and Map 
39 shows that this constellation rises in March about 8 p.m. 

SATURN. 

The index to Saturn is used in the same manner as the indexes to the other planets 
already described. 



INDEX TO SATURN. 



A.D. 


Jan. 


Feb. 


Mar. 


April. 


May. 


June. 


July. 


Aug. 


Sept. 


Oct. 


Nov. 


Dec, 


1892 
1893 


41 
42 


41 
42 


41 
42 


41 
41 


41 
41 


41 
41 


41 
41 


41 
42 


41 
42 


41 
42 


42 
42 


42 
42 


1894 
1895 

1896 


42 
42 
43 


42 
42 

43 


42 
42 
43 


42 

42 
43 


42 
42 
43 


42 
42 
43 


42 
42 
43 


42 
42 
43 


42 
42 
43 


42 
42 
43 


42 
43 

43 


42 
43 
43 


1897 
1898 
1899 


43 
43 
44 


43 
43 

44 


43 
43 
44 


43 
43 
44 


43 
43 
44 


43 
43 

44 


43 
43 

44 


43 
43 
44 


43 
43 

44 


43 
43 
44 


43 
43 
44 


43 

44 

44 


1900 
1901 
1902 


44 
45 
45 


44 
45 

45 


44 
45 
45 


44 
45 

45 


44 

45 
45 


44 
45 

45 


44 
45 
45 


44 
45 

45 


44 
45 
45 


44 
45 
45 


44 
45 
45 


44 
45 
45 



Examples to Illustrate the Use of the Index to Saturn. 

Example 1. — When is Saturn in opposition in 1894, and in what part of the heavens 
does it then lie % 

Solution. — The opposition is in April, and the index to Saturn gives Plate 42. The 
locality is near Virgo, and the phase No. 4, Plate 8. 

Example 2. — Where is Saturn in August, 1901 ? 

Solution. — The index refers to Plate 45, showing that Saturn is about Sagittarius or 
Capricornus. As the opposition in this year is in July, the phase shown by 
Saturn is No. 7 on Plate 8. 

Example 3. — When does Saturn set in August, 1898 ? 

Solution. — The Index refers to Map 43, showing that Saturn is in Libra, and Plate 45 
shows this constellation setting at 10 p.m. in August. 



38 INTRODUCTION". 



THE NAMING OF AN UNKNOWN PLANET. 

The beginner will sometimes notice a bright star-like object which he knows is not a Star, 
for it is not represented on the maps. He infers that it must be a planet, and he desires to 
find its name. 

It may be assumed that the object must be one of the four bodies — Venus, Mar?, Jupiter, 
or Saturn. With the aid of the Planetary Index it is a simple matter to determine which of 
the four the unknown obj ect must be. 

To illustrate the process by an example. I shall suppose that a planet is noticed in the 
west at 10 p.m., in April, 1893. Plate 41 shows that the situation of the body must have 
been about Gemini, for this is the westerly part of the track of the Planets. The Planetary 
Index demonstrates that Jupiter alone occupies this region, for Mars is about Sagittarius : 
Venus about Pisces : and Saturn about Libra. The object enquired about must therefore be 
Jupiter. 

The following may serve as an illustration of the use of the monthly maps, and of the 
various indexes to the Planets : — 

On a fine evening in January, 1892, at a quarter to five, a bright object, clearly a planet, 
is low down in the sunset glow. There is another planet higher up to the east, and beyond 
that again is the Moon, about seven days old. Name the planets. 

The planet low down is probably Venus. This is confirmed by the Index to Venus, which 
refers to Plate 46, for January, 1892, showing that Planet to be in Capricornus or Aquarius. 
The Index to Jupiter shows it to be in Pisces. The Moon is also seen, from page 23, to lie 
in Aries, and Plate 47 shows the position of the constellation at the time the observation was 
made. 



(39) 



CHAPTER VI.— THE STAR MAPS. 



Plates 51 to 70. 

The student who has made himself familiar with the appearance and movements of the 
Constellations, and has acquired a facility in identifying the brighter Stars, will soon feel the 
need of something further. More especially will this be the case if he has the use of a 
telescope of even moderate dimensions ; and it is to meet these requirements that the Star 
Maps on Plates 51 to 70 have been prepared. 

The first step in drawing a map is to decide on the nature of the projection to be 
employed. It must be understood that no flat maps can give a perfectly faithful representation 
of a curved surface, and whatever method of projection is resorted to, the result must represent 
the surface in a more or less distorted form. The Stars appear to be situated on the surface 
of a sphere, and however we may attempt to depict them, we cannot include any large portion 
of the sphere exactly as it appears to the eye. The form of projection which I have used 
in these maps is that known as the conical projection, and in adopting it I follow Argelander, 
who employed this method in his great Durchmusterung Atlas, which represents more than 
300,000 Stars in the Northern Hemisphere alone. 

Imagine two cones touching the sphere around the 
circle of 45° declination, north and south. These are 
intersected by tangent planes at the Poles, and by a 
cylinder touching the sphere around the Equator; see ad- 
joining figure. Each star on the sphere is joined to the 
centre, and the joining line when produced necessarily 
cuts some one of the enveloping surfaces in a point which 
is the projection of the star. The equatorial girdle and 
the two cones are each divided into six equal parts, 
which admit of being laid out flat ; and the eighteen 
parts thus obtained, together with the two polar planes, 
make up the twenty maps which represent the entire 
sphere. 

The top and bottom margins of each of these maps, 
with the exception of the first and last, are divided so 
as to read Right Ascensions. 

Only the hour lines have been drawn on the maps, 
so as to avoid overcrowding, and for the same reason 
only the circles corresponding to every tenth degree in 

Declination have been given. But by the aid of the divisions around the margin, it is easy to 
read the position of a star, or to enter any desired object with all requisite accuracy. For this 
purpose it will be found convenient to copy the scale in Declination, which is given on the 
margin of each map, on the edge of a sheet of paper. If, then, it is desired to enter on the map 
the position of any object (say a comet) whose R.A. and Declination are known, it is only neces- 
sary to set this sheet of paper so that the graduated edge cuts the top and bottom circles at 




-iO THE STAR MAPS. 

the R.A. of the object, and to put a dot on the map at the point of the scale coiresponding to 
its Declination. In the same way the position of any object entered on the map may be read 
off. In the case of maps 51 and 70, the method of reading off positions is somewhat different 
In these the declination scale will be found on the radius corresponding to 0* 1 -, 6 h -, 12 h - or 24k- 
This scale should be rotated around the centre until it passes through the star whose position 
is required. The R.A. will then be found at the point of the circumference where the scale 
cuts it, and the Declination will be read from the scale itself. The epoch for which the places 
are given is 1 c ; ] 

It has been arranged that each zone of maps overlaps those north and south of it for a 
distance of five degrees in Declination, and each map of a zone overlaps those preceding and 
following it for a space of 40 mins. in R.A. 

In order to avoid breaking up conspicuous star groups, I have made the zero, from which 
the hour circles are measured, pass through the centre of the first map (Xo. 52) of the inter- 
mediate zones, while the same circle divides the first and last maps of the equatorial zone- 
By this mode of dividing the heavens it has been found possible to comprise each of the 
more striking configurations of stars within a single map. The only exception is the great 
square of Pegasus, which will be found on Plates 52, 58, and 63. For convenience in passing 
from one map to another, the numbers of the plates which represent adjacent portions of the 
sky have been printed just inside the margin. 

In the construction of these maps I have followed, to a great extent, the Uranometrie 
Generate of Houzeau. It contains all the stars visible to the naked eye under the most favour- 
able circumstances, and the number amounts to nearly 6,000. 

In the nomenclature of the stars, however, I have departed considerably from Houzeau, 
doing away in general with letters (other than those of the Greek alphabet), and substituting, 
wherever possible, Flamsteed's numbers. 

I have followed Houzeau throughout in the estimation of star magnitudes, as by so doing 
I obtained a uniform system over the whole sky, both in the Northern and Southern Hemi- 
spheres, determined by a single observer in the same climate and within a short time. His 
work, besides, is more recent than that of Argelander, Heis, or Behrmann. I have further, for 
simplicity, limited the number of magnitudes given by Houzeau to six, namely, 1, 2, 3, 4, 5, 
and 6, which will be found sufficient for all ordinary purposes. These I have indicated on the 
maps themselves, as shown by the scale at the foot of each map, where, in addition to the size 
of the dot representing the star, its magnitude is denoted by the number of rays diverging from 
it. Thus all stars of the first magnitude possess 6 rays, those of the second magnitude 5 rays, 
and so on. The magnitude of a star may be found by subtracting the number of the rays 
from seven, except for the sixth magnitude, in which case the single ray has been omitted, stars 
of this class being represented by a simple dot. 

Throughout the maps a large number of the stars will be found accompanied by the letter 
d. This signifies that the star, though appearing as a single body to the naked eye, is in 
reality double. This does not however denote duplicity, or a binary character in the usual 
sense of the word, but merely that the point of fight thus characterized will be found to break 
up into two with the aid of a small telescope. A number of variable stars have been inserted in 
the maps, as they must always be objects of interest to the student of Astronomy. In the case 
of those stars which, though variable in brightness, are always bright enough to be seen. I have 
assumed a magnitude intermediate between their greatest and least brilliancy, and printed var. 
after their designation. The fainter ones are represented by a small circle with a point at 
the centre. The folic wing is a list of the Variable Stars on these maps, selected from the 
Annuaire du Bureau des Longitudes. 



INTRODUCTION. 



41 



REGULARLY VARIABLE STARS. 



N amet Greatest and 

Least Mag. 

T Ceti 52 — 6'7 

R Andromedre 7-1 — <12 - 8 

R Sculptoris 5-8 7-7 

Ceti 3.3 _ 8 . 8 

P Persei 3-4 _ 4-2 

£ Persei 2*3 — 3-5 

*■ Tauri 3-4 — 4*2 

R Leporis 6-5 — 8*5 

U Ononis 6*9 — <12'0 

n Geminorum 3 2 — 4-0 

T Monocerotis 6*1 — 7 -8 

S Monocerotis 4*9 — 5*4 

£ Geminorum 3 "7 — 4-5 

R Geminorum 7-2 — <13*5 

L 2 Puppis 3-5 — 6*3 

S Canis Min 76 — <ll-0 

U Geminorum 9 3 — 13*1 

N Velorum 3*4 — 4*4 

R Carinse 5*0 — 9'7 

R Leonis 5'9 — 9*7 

1 Oarinse 3*7 — 5-2 

IT Hydra? 4-5 — 62 

R Hydra 4-5 — 9*7 

S Virginia 67 — 12-5 

8 Librae 5*0 — 6*2 

S Herculis 67 — 12-3 

3 Sagittarii 40 — 6-0 

y 1 Sagittarii 50 — 6 - 5 

Anon 5*2 — 7 "5 

k Pavonis 4 — 5*5 

p Lyrse 3-4 — 4*5 

R Aquilae 6 -9 — 11*2 

X Cygni 5-2 — 13'5 

r\ Aquil-e 35 — 4*7 

Anon 6-8 — 8*0 

T Vulpecula3 5*5 — 6 '5 

S Cephei 3*7 — 4-9 

R Cassiopeia? 5*9 — 10'9 



R.A. 



Dccl. 



01 


1. 16m. 


- 20' 


43 





18 


+ 37 


55 


1 


21 


- 33 


9 


2 


13 


- 3 


31 


2 


57 


4- 38 


22 


3 





+ 40 


29 


3 


54 


+ 12 


9 


4 


54 


- 14 


59 


5 


49 


+ 20 


9 


6 


8 


+ 22 


33 


6 


19 


+ 7 


9 


6 


34 


+ 10 





6 


57 


+ 20 


45 


7 





+ 22 


53 


7 


10 


- 44 


26 


7 


26 


+ 8 


34 


7 


48 


+ 22 


19 


9 


28 


- 56 


29 


9 


29 


- 62 


16 


9 


41 


4- 11 


59 


9 


42 


- 61 


56 


10 


32 


- 12 


45 


13 


23 


- 22 


40 


13 


27 


- 6 


35 


14 


55 


- 8 


2 


16 


46 


+ 15 


8 


17 


40 


- 27 


47 


17 


57 


- 29 


35 


18 


41 


- 5 


50 


18 


45 


- 67 


24 


18 


46 


+ 33 


13 


19 


1 


+ 8 


3 


19 


46 


+ 32 


37 


19 


47 


+ 


43 


20 


40 


+ 17 


40 


20 


47 


+ 27 


35 


22 


25 


+ 57 


48 


23 


52 


+ 50 


43 



IRREGULARLY VARIABLE STARS, 

AND STARS WHOSE PERIOD IS NOT KNOWN. 

Nova 1572 >1'0 — ? 18 +63 

*Noval885 7'0 — <12'5 37 +40 

1 Auriga 3-0 - 4-5 4 53 + 43 

Nova 1892 4'5 - ? 5 24 + 30 

R Velorum 6*5 — 7'5 10 2 - 51 

* In the great Nebula of Andromeda. 



29 
37 
39 
21 
37 



42 



INTRODUCTION". 



IRREGULARLY VARIABLE STABS-aontinued. 

Name, Greatest and p DecL 
Least Mag. 

S Carinas 62 — 90 10b. 6m. - 60° 58 

<) Argus >l-0 — S'O 10 40 - 59 4 

Schjellerap 152 5-5 — 6-5 12 40 -46 3 

Anon, 5-5 — 6'5 13 28 - 12 37 

T Centauri 6'1 — 93 14 8 -59 22 

R Corona? 5S — 13"0 15 44 - 2S 32 

= T Corona; | "° 9o lo 00 * io 

Xo ™ 1S60 .. | 7-0 — <12-0 16 10 - 22 41 

= 1 bcorpu \ 

Nova 1848 5'5 — 12-5 16 53 - 12 43 

a Hereulis 3-1 — 3-9 17 9 +14 31 

Nova 1604 >l-0 — ? 17 23 -21 23 

Nova 1670 3-0 — ? 19 43 -27 1 

Nova 1876 3 "2 — 13 ! 5 21 37 - 42 18 

fi Cephei 4"0 — 5'0 21 40 - 53 14 

19 Piscium 4'5 - 6'2 23 40 + 2 50 

The place? in the above list? are given for the epoch 1880. a.? it was considered that 
the advantage of having it identical in this respect with the epoch chosen for the charts, 
would counterbalance any advantage to be gained by choosing a later date ; there is also a 
convenience in having the star places for the same epoch as Webb has selected in his excel- 
lent work, Celestial Objects for Common Telescopes. 

In many of the maps will be found an asterisk, closely accompanied by a date. This 
marks the radiant point of a meteor shower, and the date accompanying it is that on which 
the shower takes place. The following is a list of such radiant points, which is based on a 
similar list by Mr. W. F. Denning, in The Admiralty Manual of Scientific Enquiry. 1 : 

Table of Dates and Radiant Points of the Peincipal Mjsteob Showees. 









Radiant Point. 






Date of Shower. 




R.A. 






Time. 


Arc. 


Decl. 






h. 


m. 


o 


o 


1 


January 1-3 


15 


28 


232 


- 49 


o 


January 5-11 


9 


40 


145 


— 5 


o 
O 


Januarv 28 


15 


44 


23 3 


- 25 


4 


Febraarv 5-10 


4 


56 


74 


- 43 


5 


Februarv 15 


15 


44 


236 


- 11 


6 


February 16 


11 


8 


167 


- ' 


> 


February 20 


12 


4 


1S1 


- 34 


8 


March 4 


11 


44 


176 


+ 9 


9 


April 9-12 


16 


36 


249 


+ 51 


10 


April 18-20 


17 


56 


269 


- : 


11 


April 30 


21 


44 


326 


_ o 


12 


May 11 


15 


24 


231 


- 27 


13 


May 30 


22 





330 


4- 28 


14 


June 13 


20 


40 


310 


- 61 


15 


June 25-30 


16 


52 


253 


- 47 


16 


July 23-25 


3 


12 


45 


- 43 



Marked by the star 4 Sextantis. 



Marked by the star 23 PegasL 
Marked by the star ?? Cephei. 

Midway between 30 and 32 Persei. 











INTRODUCTION. 




Table of Dates and Radiant 


Points 


No. 


Date of Shower. 




Radiant Point. 
R.A. 






Time. 




Arc. 


Decl. 


17 
18 


July 28 
August 9-11 


11. 
22 
3 


in. 

44 






o 

341 
45 


o 

- 13 

+ 57 


19 


August 21-25 


19 


24 




291 


+ 60 


20 
21 
22 
23 


September 7 
September 21 
September 25 
October 15 


4 

2 

6 

7 


8 

4 

36 

4 




62 

31 

99 

106 


+ 37 
+ 19 
+ 43 
+ 23 


24 


October 18 


6 







90 


+ 15 


25 


November 1 


2 


52 




43 


+ 22 


26 


November 12-14 


9 


56 




149 


+ 23 


27 


November 13-18 


10 


20 




155 


+ 40 


28 


November 19-23 


4 


8 




62 


+ 21 


29 


November 27 


1 


40 




25 


+ 43 


30 


Nov. 30— Dec. 4 


12 


56 




194 


+ 43 


31 


December 1-10 


7 


48 




117 


+ 32 


32 


December 6 


5 


20 




80 


+ 23 


33 


December 10-12 


7 


12 




108 


+ 33 



43 



Marked by the star 15 Arietis. 



Marked by the star 51 Tauri. 



Plates 71 and 72. 

As I have already pointed out, the region of the sky which corresponds to any one of 
the general series of maps, is indicated by the dotted lines in the series of monthly maps 
(Plates 39 to 50). This, however, is chiefly useful at localities about the latitude of the 
British Islands. For the convenience of those living in other latitudes, to whom it is hoped 
this Atlas will recommend itself, as well as to enable the student at home to choose the 
maps suitable for his purpose with greater rapidity, I have added the Northern and Southern 
Index Maps (Plates 71 and 72). In these the principal constellations are marked, and the 
outlines of each map of the general series, with the numbers of the corresponding plates in 
bold figures. Each Index Map includes from the Pole to 25° beyond the Equator, so that 
both contain the series of Equatorial maps. Around the circumferences is marked each hour 
of R.A. The Declination is not indicated, but it can be ascertained with sufficient accuracy 
for the purpose of finding the required map by remembering that the Equatorial zone extends 
to 25 Q Declination, and the intermediate zones to 70° Declination, while each zone overlaps 
that above and below it by 5°. 



PRECESSION. 

The Precession of the Equinoxes, or the slow motion of the Earth's axis, in consequence 
of which the intersection of the Equator with the Ecliptic travels along the latter, brings 
about a constant change in the R.A. and Declination of the Stars from year to year. It is thus 
clear that the values of these quantities as read from the maps will only be strictly accurate 
at the epoch for which the maps are drawn. In order to find the R.A. and Declination for any 
other date, it is necessary to apply a correction for this precessional effect, and if it is desired 
to mark upon the maps the position of any star or other object whose co-ordinates are given 
for a date different from that of the Atlas, a similar correction must be applied. 

It must, however, be borne in mind that no change takes place from this cause in the 



44 



INTRODUCTION. 



relative position of the stars, — the effect being merely to give the whole system of Right 
Ascension and Declination circles a shift, and thus to alter the positions of all the stars v>ith 
regard to them. 

For accurate astronomical work, the correction for precession must in general be computed 
to a small fraction of a second, and elaborate tables have been prepared to facilitate this 
operation ; but for all purposes coming within the scope of the present work, the following 
tables will be foimd amply sufficient. 

That given on this page contains the correction to the R.A. for 10 years' precession. The 
quantity found in the table is to be added, with the sign there indicated to the R.A. at any 
time, in order to obtain the R.A. for an epoch 10 years later, or it is to be subtracted to find 
the R.A. at an epoch 10 years earlier. For intervals other than 10 years a proportional 
allowance must be made. The top and bottom lines contain the Declination, and the first 
and last columns the R.A. 

For most purposes it will be sufficient in finding the precession to take the R.A. to the 
nearest whole hour, and the Declination to the nearest multiple of 10 degrees. If the star is 
situated in the Xorthern Hemisphere, we find its Declination in the first or last line, and run 
the eye down the corresponding column till we reach the line which contains the stars R.A. in 
the first column ; the corresponding figure in the table is the precession in R.A. for 10 years. 
If the star is in the Southern Hemisphere, we look for its Declination as before, but we find its 
R.A. in the last column. 

The second table, containing the correction to the Declination for 10 years, is still more 
simple. We have merely to enter it with the nearest hour of R.A. in the extreme columns, 
and we find in the central column the corresponding correction to the Declination. For all 
R.A.'s found on the left side the correction is positive, and negative for all those on the right 
side. 

The signs of the precessions given in both tables show the correction necessary to bring 
the star's place up to a subsequent date ; to bring it back to an earlier date the signs must 
be altered. The table of precession in R.A. extends to 70° north and south of the Equator, 
so that it is applicable to all the stars except those around the Xorth and South Poles, 
contained in Plates 51 and 70. 



Table toe Peecessiox in R.A. 



E.A.forX.Decl. 0° 10 : 20° 


30° 40° 50 Q 60° 70° E.A.forS.Decl. 


h. h. 

18 or IS 

19 „ 17 

20 „ 16 

21 „ 15 

22 „ 14 

23 „ 13 

, 12 

1 .. 11 

2 .. 10 

3 „ 9 

4 „ 8 

5 „ 7 

6 „ 6 


m. 

+ 0-51 
•51 
•51 
■51 
■51 
•51 
■51 
•51 
•51 
•51 
•51 
•51 

-^0-51 


m. 

+ 0-47 
■47 
•48 
•48 
•49 
•50 
■51 
•52 
•53 
•54 
"55 
"55 

+ 055 


m. 

+ 0'43 

•-J3 

■44 

■45 

47 

■49 

•51 

■53 

"55 

•V" 
i 

•58 

•59 

+ 0-59 


m. 

+ 0-38 
•39 
•40 
42 
■45 
•48 
•51 
•54 
■53 
•60 
•62 
•64 

-064 


m. 

-0-33 
•33 
•35 
•38 
•42 
•46 
•51 
•56 
■61 
•64 
•67 
•69 

+ 0'70 


m. 

+ 0-25 
•26 
•28 
•32 
•38 
•44 
■51 
58 
•64 
•70 
■74 
•77 

^0-7S 


m. 

+ 013 
•14 
•18 
•24 
•32 
•41 
•51 
•61 
•70 
■78 
•S5 
•88 

+ 0-90 


m. 

-o-io 

•08 

-0-02 

+ 0-08 

-21 

•35 

•51 

•67 

•82 

0-94 

1-04 

1-10 

+ 112 


h. h. 

6 or 6 

5 „ 7 

4 „ 8 

3 „ 9 

2 „ 10 

1 „ 11 

„ 12 

23 ., 13 

22 „ 14 

21 „ 15 

20 „ 16 

19 „ 17 

18 „ 18 


R.A. forN.DecL 


? 


10° 20° 


30° 


40° 


50° 


60 u 


70° 


E.A. for S. Decl. 



introduction. 
Table for Precession in Declination. 



45 



R.A. 


Precession. 


R.A. 


h. 




h. 


o 


h. 


h. 





or 


24 


+ 0-06 - 


12 or 12 


] 




23 


•05 


13 , 


, 11 


2 




22 


•05 


14 , 


, 10 


3 




21 


•04 


15 , 


» 9 


4 




20 


•03 


16 , 


, 8 


5 




19 


•01 


17 , 


, 7 


6 


» 


18 


•00 


18 , 


, 6 



Example. — The star Capella is situated in 1880 in R.A. 5 h. 8 m., Decimation + 45° '9 : 
find what its R.A. and Declination will be in 1905. 

Entering the first Table with R.A. 5 h., and Declination 50°, we find 10 years' precession 
in R.A. is + 0"77 m. Hence the corresponding correction for 25 years will be to the nearest 
whole minute + 2 m. 

Entering the second Table with R.A. 5 h., we find 10 years' precession in Declination 
is + 0°"01, hence to the tenth of a degree the correction for 25 years is negligible, so that 
we find in 1905 R.A. = 5 h. 8 m. + 2 m. = 5 h. 10 m., and Declination = + 45°'9. 

If it were required to find the place of the star at the beginning of the century (i.e., 80 
years previously), we have to multiply + 0*77 m. and + 0°'01 by - 8, and we find the cor- 
rections — 6 m. and — 0°'l, so that the place of this star in 1800 is R.A. 5 h. 2 m., Declina- 
tion + 45° -8. 

As another example, let us find the R.A. and Declination of w Draconis in 1940. Its 
place in 1880 is 17 h. 38 m. ; + 68°'8. We find from the Tables — O'lO m. as correction for 10 
years' precession, and 0°'00 as the correction in Declination ; we thus obtain for 1940 R.A. = 
17 h. 38 m. — 0*6 m. = 17 h. 37 m. to the nearest minute, and Declination + 68° "8. 

Once more, suppose that in 1950 it is announced that a comet has been seen in R.A. 3 h. 
42*9 m., and Declination + 23° "96. We find the precession in R.A. and Declination from the 
tables to be, for 10 years, + 0'58 m. and + 0°'03. Hence, to bring the place back to 1880, 
we have the correction — 4*1 m. and — 0°*21. We thus have 



1950 

Correction for Precession.. 


Comet's R.A. 
h. m. 
3 42-9 
-4-1 


Comet's Declination 



+ 23-96 
— 0-21 




. 3 33-8 


+ 23-75 



That is to say, the place occupied by the comet is indicated on these maps by the figures just 
found for 1880, so that it would be found at the time of the announcement in the centre of 
the group of the Pleiades. 



(46) 



CHAPTER VII. —SELECT TELESCOPIC OBJECTS. 



In preparing a list of objects suitable for observation with small instruments, the 
following works among others have been consulted : — Smyth's Celestial Cycle, Webb's Celestial 
Objects, Darby's Astronomical Observer, Crossley, Gledhill, and Wilson's Double Stars, and 
The Companion to the Observatory. Below the name of each object is given its position, and 
then a reference to the plate or plates on which it may be found. Nebulae and clusters are 
occasionally referred to Sir J. Herschel's General Catalogue, e.g., H 1067. 



SELECT TELESCOPIC OBJECTS. 

34 Piscium. A fine, double star, when viewed in a good telescope, 4° south and 3m. pre- 

ss, 63. ceding y Pegasi. The principal star is of the 6th mag., and the companion is of 
the 11th. The position-angle is 160°, and the distance 7""8. The colours of the 
stars are silvery white and pale blue. 

oh 5 9m S + U s?9' ^is P a * r * s an eas i er object than the last. The stars are 6th mag., white, 

58, 63. and an 8th mag. of a purplish tint. Like the preceding, the components appear 
to be relatively fixed. Position-angle 150°, and distance 11"*9. 

ok 8 ?! 1 ! 180 -! 1 ^:!-;' *^ s beautiful pair follows the last at an interval of 2m., almost in the same 
58," 63. parallel. It was believed by Herschel I. to be in motion, but later measures seem 
to establish its fixity : the position-angle is 240°, and the distance 4"'5. The 
components are respectively, 74m. yellow, and 8m. white. 

oh 4 iom S +i™'49' -^is wide double is a beautiful object in the telescope, on account of the 
58, 63. strongly contrasted tints of the components, which have been described as topaz 
and emerald. The position-angle and distance as determined by Gledhill, in 1873, 
were 338° 1, and 29" # 0, respectively. Although the stars appear to be slowly 
approaching each other, this movement is probably not of an orbital character, 
but is due to the proper motion of the principal star 

The Great Figured in Plate 14. See page 16. This object is the only nebula visible to 

Andromeda, the unaided eye. It is, both from its size and brightness, one of the two most 
0h ' 36m 52 +4 °° 35 ' famous nebulae (the other being the great nebula in Orion). This object is cer- 
tainly not a mere star cluster. At the same time, the spectroscopic evidence of 
its gaseous character is not so convincing as in some other bright nebulae. To 
study a nebula, it is well to point the telescope so that the object is just out of the 
field, and then allow it to enter by the diurnal motion. 



INTRODUCTION. 47 

The duplicity of this interesting object was discovered in 1779, by Sir n cassiopeise. 
Win. Herschel. It has thus been under observation for more than 100 years. oh " 42m 5 '2 + 57 ° ll ' 
In this period its binary character has been clearly established. According to 
Doberck, its period is 222| years, and the semi-major axis of its orbit is 9""8. In 
1856, Otto Struve found its parallax to be 0"'15, so that its light takes 22 years to 
reach us. This star is also affected with a considerable proper motion, amounting 
to 1""2 annually. The colours of the components are yellow and purple, and their 
magnitudes 4 and 7i respectively. (Gledhill, 147 0, 2 ; 5"'8, 1876). 

This beautiful double star can be detected by the naked eye between r\ and £ 36 Andromedse. 
of the same constellation. Although tolerably close, it is not a difficult object oh- 49 5 ™ - J 23 " ^ 
to measure, on account of the approach to equality in the magnitude of the com- 
ponents. They are 6th and 7th magnitudes respectively, of an orange tint. It 
seems to be of a binary character, though of long period. An orbit computed by 
Doberck, in 1875, which gives a period of 349 years, and semi-major axis 1"*54, 
represents the motion fairly well. (Dembowski, 356 0, 2 ; 1 '"3, 1877). 

The components of this star are of the 6th and 13th magnitudes respectively, piscium. 
the position-angle is 226° '5, and the distance 9". It seems probable that the com- lh - 7l J; ^ 8 23 ° 57 ' 
panion is variable. 

This is in some respects the best known and most practically important star a ursae Min. 
in the sky. On account of its proximity to the North Pole, it appears to the lh i^^fss 40' 
naked eye to be almost devoid of the ordinary diurnal movement in which the sl 

others stars partake. In early days, before the invention of the magnetic com- 
pass, the navigator used to steer his ship by the indications of the Pole-star. 
In the modern Observatory it still maintains a position of importance as a mark 
for the adjustment of instruments, although the motion which it shares in com- 
mon with all the other stars, but in a smaller degree than most, can no longer be 
overlooked. It is situated at such an enormous distance from the Sun, that its 
parallax is almost insensible, and its light must take at least 63 years in reaching 
us. 

The principal star, which is of the 2nd magnitude, is attended by a small 
companion, about 9 J in magnitude, situated at a distance of 19", and position- 
angle 212°. So far there does not appear to be any evidence of a change in the 
relative position of the components. The Pole-star can easily be found in the 
sky by the aid of a and (3 Ursse Majoris, " the pointers," as they have been 
called. An imaginary line drawn through these two, and continued about five 
times the distance separating them, will pass near the Pole-star, which, once 
found, will be easily remembered by its apparent fixity in the sky. 

This star is interesting as having been discovered as a double star by Hooke y Arietis. 
as early as 1664, when he was observing the Comet of that year : " a like instauce lh - 47m 5 ^" 18, 42 ' 
to which I have not else met with in all the heavens." Its components are of 
the 4th magnitude, and of a white and bluish colour respectively. The distance 
is 8"'3, and position about 359°. There is a slight change in the distance, but 
whether orbital or parallactic, is not yet clear. 



45 iyTEODUCi: ■: N 

a Kschnn. A beautiful double star, of which the components are of the 5th and 6th inag- 

Jb - 5tb *^ + ru ' nitudes respectively. The colours have been variously stated, but are generally 
designated green and bluish. The position-angle appears to be slowly diminish- 
ing, being now (1892 3i " \ and the distance 3 "5. 

■ a. -.-.:'.:: n r '^ This object, which is the second in a conspicuous line of four stars leading 

Ih " '5^53. il ^ fr° m a P ers ^i t0 a An'iromedse, is one of the finest objects of its class in the 
heavens. In most telescopes it appears as a double, composed of two stars, 
yellow 35, and sea-green 5*5, respectively. The latter is situated at 62 z , 10", and 
appears stationary with regard to the primary. In 1842, Ottc Srruve discovered 
that the companion was itself double, :~ ; few* components being nearly of the 
same magnitude. Both position-angle and distance appear to be diminishing 
slowly, being at present 104° and 

i TrianguiL An ex quMte double star, of which the primary is yellow and of the 5th 

*" ^hl 9 ***' magnitude, and the companion blue and 7th magnitude. The position-angle is at 
present about 74°, and the distance 3 o. It may possibly be binary, but the 
motion is very slow. 

The Clusters ia This splendid pair of clusters, viewed on a clear night, when the Moon is 

ah-run^^Sr ar a ^ sent > ^ orm tne most striking sidereal spectacle in the Xorthem heavens. They 
52, 53. can easily be found as a condensation of brightness in the Milky TVay, on the line 

joining a Persei with c Cassiopeia?, at about three-fifths of the distance from the 
former. The preceding cluster is the richer of the two, and contains hundreds of 
stars from the 7th magnitude down to the extreme limits of visibility, grouped in 
the " enchanting disorder of Mature ~ within a space of about half a degree square. 
Near the centre is a beautiful horse-shoe or coronet of 6 stars, graduated in bright- 
ness from the 8th to the 10th or 11th magnitude, and in other parts of the mass 
several minor groups of somewhat similar form may be detected. 

The other cluster follows on the same parallel at 3 minutes interval. It can 
a somewhat smaller space, and does not present such a wealth of stars as the 
preceding object The principal features of this group are two conspicuous triangles 
of 9th, 10th, and 11th magnitude stars on its preceding side. 

Nebula H 527 An elongated nebula, which presents the appearance of a flat ring seen almost 

2h^^Mr47' edgewi— . Lis covered by Miss Herschel in 1":: -ing only a Xewtonian of L~ 
52, 53. inches focal length, and power of 30. Possibly variable, for sometimes very diffi- 
cult to see. 

P n : A remarkable triple star. The primary is a 4th magnitude star, of a yellow- 

siLnff^SrW ^ n goI ™"* attended at a distance of 8', and position-angle 108°, by an 8th magni- 
51, s±, 53. " tude star of a fine blue tint, which, so far, appears to have remained stationary 
with regard to the primary. In 1779, Sir Win. Herschel discovered that the 
primary was itself a close double. This nearer comes is situated at a distance of 9 . 
and position-angle 265\ and is probably in slow orbital motion. All three are 
affected by a common proper motion. 

v Ceti. A double star, of which the components are of the 5th and 10th magnitudes, 

sb- 30n ^* r 9 and the colours pale yellow and blue respectively. The distance is 7*"5, and the 
position-angle 83 3 . The companion is a difficult object to most observers, though 
Webb found it " easy with Scinch in 1861." 



INTRODUCTION. 49 

A double star of the 6th and 10th magnitudes respectively. The companion, 8t Ceti. 
which is situated at a distance of 4""6, and position-angle 316°, partakes of the ' ' 5m 5S ~ 1 13 ' 
considerable proper motion of the primary, and is probably in slow orbital motion 
around it. A difficult object. 

A triple Star— A of the 4th, B of the 10th, and C of the 9th, magnitudes. 2h 3 6l ^ e ^ 4 3' 
A and B are affected with the same proper motion, amounting to nearly 1" 53. 

annually, and probably form a binary system. The distance is 16"'5, and the 
position-angle 296° at present. C is situated at a distance of 68", and position- 
angle 216°, and is almost certainly not in physical connection with the other two. 
The colours are yellow, violet, and grey. 

A beautiful double star. Components — 3*5 pale yellow, and 7 blue, with ^7 Ce +rw 
common proper motion. Probably a very slow binary. The position-angle is 58. 

290°, and distance 2" 7. 

A coarse quadruple star, of which the components are — A, 3rd magnitude, h 41 Arie n is o , 4fi , 
white ; B, 13th magnitude, blue ; C, 11th magnitude, orange ; D, 9th magnitude, ' 53. 
grey. Burnham gives the following positions for 1879 : — 

Position Angle. Distance. 

AandB 266°0 21"2 

AandC 203-5 34'0 

AandD 230*2 125*9 

And adds, lC There seems to be considerable change in 0, and perhaps some in B." 

This is one of the most wonderful stars in the heavens. From early times it ft Persei (Algol 
was known as an extraordinary variable, and obtained in consequence its name, 3 ' m ' 53 . 
Algol, or "the Demon Star." For 2d. 12 h. this star remains of the 2nd magni- 
tude. Within 4i hours it falls to the 4th magnitude, and remains so for 18 m., 
after which it begins to recover its brightness, and within another 4^ hours it has 
regained the 2nd magnitude. These changes are repeated with regularity in a 
period of 2 d. 20 h. 48 m. 55 s. 

Up to the year 1888, the cause of this variability was unknown. Prof. 
Vogel's recent spectroscopic researches have shown that the changes in Algol's 
brightness are caused by the passage of a darker satellite, which revolves around 
the primary in the same period as that in which the variations take place. 
Algol is therefore a double star, belonging to a novel class, which contains a few 
other somewhat similar objects. The distance between the components is about 
3,000,000 miles. 

This 1st mag. star, conspicuous for its rudely colour, is the principal object in a Tauvi 
the group of the Hyacles, which is shown in Map 59, 42 m. following, and 8° tt ^^5? } lff 
south of the Pleiades. It has a faint companion of the 12th mag., at 35° posi- 59. 

tion-angle, and 115" distance. Burnham discovered a very minute attendant of 
the 14th mag. at 111°, 31", which is a severe test for all but the largest telescopes. 

Aldebaran is affected by a considerable proper motion, amounting to nearly 
£th of a second annually. An occupation of Aldebaran by the moon, which not 
unfrequently occurs, is a striking phenomenon. 

E 



50 



INTRODUCTION. 



7 Cameiopar- A triple star, long known as a double, composed of a 4th mag. white star. 

4h.4Sm.-f 53° 33' accompanied at position-angle 239°, distance -27', by an 11th mag. orange-coloured 
attendant. In 1864 Dembowski discovered a close 8th mag. olive-coloured com- 



/3 Orionis (Rigel 

5h. 9m. — 8" 2(7 

59. 



panion, at a distance of 1"'2, and position-angle 309°. 

A very difficult object in any but the best telescopes, notwithstanding the 
large distance of 9""5. The brilliance of the principal star, which is of the 1st 
mag., overpowers the feeble luminosity of the attendant of the 8th mag., situated 
at position-angle 200°. Burnham found the companion double with the Chicago 



Cluster h 1067 Sir Wm. Herschel describes this as "a pretty compressed cluster, with one 

5h.i2rZ" S 39<>i3' large star, the rest nearly of a size." The principal star is of the 8th mag., and 
" 3 - of a bright orange colour. 

Cluster h 1119 A tine cluster, described by Admiral Smyth as " an oblique cross, with a 

5h.2im. r -f s'ostr pair of large stars in each arm, and a conspicuous one in the centre, the whole 
53 - followed by a bright individual of the 7th mag." There are several wide doubles 

scattered through it, and the whole region is very beautiful. 

32 Ononis. A difficult double of the 5th and 7th magnitudes, both white. Position- 

5h ' 2iD 59 + 5 ° 51 ' angle and distance are both diminishing, and were, in 1887, 189° and 0""44 re- 
spectively. Probably binary. 

c Orionis. ^ "^^e double star, the preceding of the three gems in Orion's belt. The 

5h. 26m.- 0= 23' primary is a brilliant white star of the 2nd mag., and the companion a pale violet 
of the 7th mag. The position-angle is 359 Q , and the distance 53". Bivrnham 
added another faint 14th mag. attendant at pos. 227°, distance 34 ". 



59. 



Nebula H 1157 

Taurus. 
5b.27m.-t- 21° 56' 

io, 59. 



Great Nebula in 
Orion. 

5h. 29m.— 5 ; 2S' 
59. 



This object was first seen by Bevis in 1731, but accidentally discovered again 
by Messier when observing the comet of 1758 ; a circumstance which led to the 
formation of his famous Catalogue of 103 Clusters of Stars and Nebulae, which 
was the first of its kind. This is the ■ Crab Nebula " of the Earl of Eosse, 
whose great 6-foot reflector succeeded in resolving it into a cluster of stars. 

Figured in Plate 14. See p. 16. This, the famous nebula in Orion, and 
the nebula in Andromeda, are by far the grandest objects of their class visible 
to observers in the Northern Hemisphere. Even in a small telescope many of 
the features of the Orion nebula are to be discerned, and in a great instrument 
the object is not surpassed in interest by any other telescopic spectacle. The 
bluish hue of the great nebida seems connected with the fact that the spectroscope 
reveals the presence of Hydrogen. Multitudes of stars are scattered over the 
field, and framed in the densest part of the nebula lies the superb multiple 
star, 9 Orionis. 

39 \ ononis. A beautiful double star, situated in a splendid region. The components are 

5h. 2 9™-+ 9 ° 51 ' 4th mag. pale yellow, and 6th mag. purplish, respectively. This star, with <pi and 

(p. 2 Orionis, form a triangle to the naked eye, which constitutes the head of Orion. 



INTRODUCTION. 



51 



A beautiful multiple star. Iu most ordinary telescopes it presents the 
appearance described by Sir Wm. Herschel as " a double-treble star, or two sets 
of treble stars almost similarly situated." In larger instruments both sets are 
seen to be quadruple. With the great Dorpat refractor, Struve found the group 
to consist of 15 stars. 

This, the following of the three, stars in Orion's belt, is composed of three — 
A, 2nd mag., yellow ; B, 6| mag., purplish ; and C, 10th mag., grey. B is situated 
at position-angle 157°, distance 2""4, and appears to be in motion relative to A. 
C is situated at position-angle 8°, and distance 60", and in its case no relative 
motion has been detected. 



<t Orionis. 

6h. 33m. - 2° 40' 

59. 



£ Orionis. 

5h. 35m. - 2° 1 

59. 



A glorious cluster, supposed by Messier to be partly nebulous, but resolvable clu ^ er h 1295 

with moderate means into about 500 stars from the 10th to the 14th magnitudes. 5h.44m.+ 1 32°32 / 
" Even in smaller instruments extremely beautiful, one of the finest of its class. 53 ' 54, 

Gaze at it well and long." — Webb. 



a Orionis 

Betelgeux. 

5h. 49m. + 7° 23' 

59. 



This brilliant object can scarcely be put in the category of double stars on 
account of the distance (161") of the companion, discovered by Sir Wm. Herschel 
at position-angle 152°. It is conspicuous for its ruddy orange colour, which con- 
trasts very strikingly with the cold blue tint of /3 (Rigel) when compared with 
the naked eye. It is irregularly variable in brilliance, but is at all times a striking 
object in the telescope. Huggins and Miller find its spectrum to be of a remark- 
able type. 

A very striking triple star, composed of A, 5 mag. ; B, 5| mag. ; C, 6 mag. ; *£ ^m -^?' 
all white. B is situated at 131° and 7" distance ; C at 124°, 9"'5. There is also ' 59. 
a fourth star of the 12th mag. at 56°, 26". 

This magnificent object has attracted attention from the earliest times as a Canis Majoris 
being the brightest star in the heavens. It was hence regarded as being our 6h.40m. r - i6 Q 33' 
nearest neighbour, but modern research has proved that it is far more remote 69 - 

than many telescopic stars. Gill and Elkin fixed its parallax at 0""39. From 
certain irregularities in its motion, Bessel suggested in 1844 that it was in orbital 
motion around a darker companion — an idea which was strikingly confirmed by 
Alvan Clark's discovery in 1862 of afaint companion, in position-angle 84°'5, and 
distance 10''4. It is now an extremely difficult object. Remarkable investiga- 
tions on the spectrum of Sirius and other stars of an allied character reveal the 
presence of Hydrogen. The orbit of this double has been investigated by several 
computers. The latest of these— Mr. Gore's — gives a period of 58 '47 years, 
eccentricity 0'4055, and semi-axis-major 8"*58. 



A pretty double star, of which the primary is of the 4th magnitude, white? * Gemmorum. 

J 7h. llm.+16°45 

59. 



and the companion 11th magnitude, yellowish. Suspected of variability. 



A rather difficult double star, of which the components are 3| magnitude, 8 Geminorum. 
white, and 9th magnitude, purple, respectively. The companion is situated at 7tL 1 g m> J 9 22 ° 12 ' 
194°, 7" at present. The position-angle is slowly increasing. 



-; 



INTRODUCTION". 



a Gerainonim 

(Castor) 
7h- 25m -r32 Q 9' 

a 



e Greminorum. 

7li. 37m. 4-24 --'. 

, 39. 

11 Cancri. 
Sh-lm. -£-2*f 50' 

54. 

~ Cancri. 

... - - li° r 
59, 60. 



This, which Sir John Herschel calls the largest and finest of all the double 
stars in our hemisphere, is an excellent object for small telescopes. It was the 
first star shown to be certainly of a binary character : the first orbit being computed 
by Sir John Herschel, who attributed to it a period of 233 years. Subsequent 
observations have increased this nearly four-fold, the latest researches pointing to 
a majestic period of about 1000 years. The components are almost equal in 
brightness, their magnitudes being 3 and 3h respectively. The position-angle is 
at present about 230°, and the distance - T : 

A very beautiful double star : component -:_ 21 unitude, orange, and 10th 
magnitude, blue, respectively. Position-angle 231 c "9, distance 6". 

A double star : the ecmpoaaat "\_ m pri&nde, pale yellow, and 12th mag- 
nitude, lilac. Position-angle 219°, distance 3". 

One of the most rem ark able multiple stars in the heavens. It is composed 
in the first place of two stars, A and B, of the 5 and 5*7 magnitude respectively, 
whose orbit has been well determined. These two revolve around each other, in 
a period of 60 y- . I 1 distance of less than 1* and are accompanied by a third 
star, C, of 5 "5 magnitude, which revolves around the centre of gravity of all in an 
opposite direction. From irregularities in the motion of C, which take place in a 
period of 17^ years, it is concluded that it is but a satellite of an invisible body 
around which it revolves in that time, describing an ellipse with a radius of about 
one-fifth of a second, and that the two together circle around A and B in 600 01 " '. 
years. 

Ppesepr ^ fijLQ duster of stars, which can be ietected bv the naked eve as a nebulous 

"54, so." ' patch of light, a little to the south, preceding -v Cancri. A fine object in small 
telescopes. 

s Hydra?. A beautiful double star, of which the components are — 3'S magnitude, yellow, 

ah - Wn J )> + " 6 ° a1 ' and 7*8 magnitude, blue, respectively. The position-angle is increasing, and is at 
present about 229° ; the distance 3" '3. It is attended at 192°, 20" by a 13th 
magnitude companion. 

Cluster h 1712 In this cluster Sir Wm. Herschel saw above 200 stars at once in the field of 

sh. 45m??L2° 15' view from the 10th to 15th magnitude. 
ml 

toaBK This very close and difficult double star has been under observation for 

4- 9° 36' nearly a whole revolution, but owing to the dirnculty of making the measures, its 
orbit is not so certain as would otherwise be the case. It was discovered to be 
double by Sir Wm. Herschel, in 17S3, and the latest investigation of its orbit — 
that by Doberck — gives its period as 110*82 years. The components are of the 
6 th and 7 th magnitudes respectively, but as the distance is never more than about 
l 7 , it requires a powerful telescope. 



R. Leonia. 
Oh. 41m. -l-ir 59' 



This is a remarkable variable star which ranges from 5 '9 to 9 "7 in magnitude. 
In all stages of brilliance it is specially to be noticed on account of its fiery red 
colour. Its spectrum, when near its maximum brightness, is characterised by 
bright hydrogen lines. 



INTRODUCTION. 53 



Two fine nebulae, separated by half a degree. The preceding is a bright oval Nebu J® J 1 1949 > 

nebula of a white colour, with a central condensation, and several small stars Ursa Major. 

in the neighbourhood. The other is a long narrow object, somewhat paler. 9hl i6 ^^ 9 ° 41 ' 
Huggins finds the spectra of both nebulae similar to that of the great nebula 
in Andromeda. 

A very fine double star, composed of a 2nd magnitude, orange, and a 4th iq^I^+^w 
magnitude, reddish green. The orbit has been computed by Hind and Doberck. ' 54, bo. 
The latter estimates its period at 407 years, and its mean distance at 2". There 
is a 7th magnitude star at position-angle 293°, and distance 229". 

This may be taken as a type of these strange objects, great globes of gas, ? lc ] ne * a J7 2 
remarkably contrasted with nebulae of the more ordinary types by the definite Hydrar ' 
nature of the margin which surrounds them. 10b " 19 S'.~ 18 ° 2 ' 

A neat double star in a fine field. The primary is of the 7th magnitude, 35 Sextantis. 
yellow, and the companion of the 8th magnitude, blue. The position-angle is 10b ~ 87l ^ ' +5 ° 23 ' 
240°, and distance 6" '8. 

A pale yellow star of the 3rd magnitude, accompanied by a 13th magnitude tfLeonis. 
of a blue tint. It is interesting as being one of the stars observed by Flamsteed, in llh - |™"g" 2r 11 ' 
1690, with the planet Uranus, which he then took for a fixed star. 

This object appeared to Messier merely as a formless spot of faint light. In Planetary 
ordinary telescopes it presents the appearance of a faintly illuminated disc about ursa^iajor. ' 
the size of Jupiter. In the most powerful telescopes it is found to be of a llh - 8m ^+ 55 ° 40 ' 
complicated structure. The Earl of Rosse found two condensations surrounded 
by spirals in opposite directions, from which it obtained the name of the " Owl 
Nebula." This nebula gives a spectrum of bright lines, from which its gaseous 
character may be inferred. 

This beautiful double star is in some respects the most interesting of its class. K Ursse Ma |° r i|-, 
On account of the approach to equality in the brightness of the components (7 '3 * ' 55. 
and 8 2), the measures are not very difficult, though the distance is small, 
amounting to about 3" at most. The orbit of this system has been frequently 
computed. The period is 60*79 years, according to Duner. 

A double star, composed of a 4th magnitude, pale yellow, and a 1\ magni- \gm°+ii<i2' 
tude, light blue. Supposed by Smyth and Dawes to be a binary system, but this " ™6. ' 
is doubtful. Position-angle is 70°, and distance 2"*8. 

A close double star, of which the components are— A, 4th magnitude, white, r crateris.^ 
and B, 10th (?) magnitude, grey. The position-angle and distance of B are 98° llh - 19 JJ;~ ir1 ' 
and 5" respectively. 

An interesting double star, A, 7th magnitude, white ; B, 9| magnitude, pur- 65 Ursse Mm. 
plish. Position-angle 36°, distance 3'"8 ; attended at position-angle 113°, and llh,49l 5 n 5. + 
distance 63", by a third star, C, 7th magnitude, white. 

A remarkable nebula, with three spiral branches springing from a central g^Nebjk 
condensation. i2h. 13m. + 15° 4' 

60, 61. 



54 INTRODUCTION. 

BereniT ^ s Pl en did double star, of which the components are — 5 - 5 magnitude, orange, 

i2h.29m.+i9 , 2' and 7th magnitude, lilac. Position-angle 271°, distance 20". The colours form a 
"striking and beautiful contrast." — Webb. 



61. 



121? aiim^flr 4*' ^ mos ^ interesting binary system, consisting of two stars of the 4th niagni- 

6i". tude. A study of its movements led Sir John Herschel to predict, in 1832, that 

within the next year or two its distance (which in 1831 was 1"'5) would close up 
to such an extent, "that none but the very finest telescopes will have any chance 
of showing this magnificent phenomenon." This prediction was verified in 1836, 
when the Dorpat refractor alone was able to elongate the star, all others seeing it 
as a single point. Many orbits have been computed for this pah*, the best giving a 
period of 185 years. It is at present not a difficult object to divide, the distance 
being about 5". 

i2h" 50m + 3s c '5$ "^ Ter ^ eas y anc ^ interesting double. It forms, with the three stars of the 

55. Great Bear's tail, a quadrilateral that could be circumscribed by a circle. Magni- 

tudes 2'5, 6'5. Position 225°, distance 19"*8. 

coma BerenfcS ^ n * s ^ a nne nebula, but, like most of these objects, requires a large telescope 

i2h.5im.+22°20' to make it effective. 

55, 61. 

Nebula h 3453 j^ instructive object, as tvpical of a certain class of clusters of minute stars. 

Coma Beremcis. . . 

ioh. 7m. + is 47' It is not effective in any instrument under four inches aperture. 

i3h i9m^i a 55'33' Probably the best known double star in the heavens, and certainly one of the 

55. easiest to find and most effective to look at in a small telescope. It is the middle 

star of the Bear's tail, and the adjacent Alcor is doubtless connected with the 
pair. Magnitudes 3, 5. Position 147° '4, and distance 14"'4. The larger star of 
the pair has been demonstrated by the spectroscope to be itself a close double, 
the mass of the two being forty times the mass of the Sun. Thus, counting Alcor, 
we have a marvellous group of 4 associated Suns. 

N can a ven°' 2 Lord Rosse*s great telescope at Parsonstown gave the first indication of the 

i3b. •25m.-r47 ; 49' spiral nature of this object, which has been completely established by the won- 
derful photographs that Mr. Isaac Roberts has obtained. In a small instrument 
this particular feature will not be seen, but an interesting pan of nebula is the 
appearance presented. 

Nebula h 3636 a globular cluster of stars when seen in a large telescope, and a nebulous 

Can. ^ en. ° . or-; 

i3b.37m.+2s J 5S' spot when seen in a small one. 

55. 

a Bootis. ^ Areturus. Easily recognised by prolonging the sweep of the Bear's tail, 

^ij " This is one of the gems of the sky, a first magnitude star, with a lustre about 

equal to that of Yega or Capella, and a slightly reddish hue as contrasted with 
the two stars just named. 

vwj 39 °° Seems like a nebula in a small telescope, and resolved into a cluster by a 

14b. 23m?- 5° 26' large one. 

61. ° 



INTRODUCTION. 55 

This object demands a powerful telescope. It is a close double, each of the ?Bootis. o 

components being of the 4th magnitude, the position-angle being 293° '4, and the u 1 - 3o ^+ 14 15 
distance 0"'51. 

One of the most beautiful of coloured doubles, the components being eBootis. 

yellowish and blue. The magnitudes are 3, 7, the position-angle 321°, and the 14h - 40 ^+ 27 ° 35 
distance 2"*9. 

A double star. Magnitudes 5, 7, position-angle 253 0, 9, and distance 3"'52 14h ^^°S9° 36 / 

(1888, Maw). " "i. 

An easy pair. This is a binary star. Doberck estimates the period of u Boot's. 

revolution at 261 years. The magnitudes are 5, 6, and the distance and position- 15 " °™' 6- + 48 
angle in 1877 were 5" and 238°, respectively. 

A cluster of minute stars, to the number of 200 in a powerful instrument. ^n Libra 40 3 

15h. 12m. + 2° 32' 
61. 

Magnitudes 3, 5 ; and, according to Hall, the position-angle is 190°, and the 8 Serpentis. 

distance 3"5. A fine object. 15h - 29 ^+ 10 ° 5(5 ' 

A pair of stars of nearly equal magnitude (6, 6j). The position-angle was a Corona > 

207°, and the distance 3"'*18, according to Schiaparelli in 1887. i6h.iOm.+34°io' 

56. 



This is a splendid first magnitude star, of a red colour. It has a green com- a Scorpii. 
:on of the 7th magnitud( 
3"*7 and 275°'7, respectively. 



panion of the 7th magnitude. Dawes, in 1864, gives its distance and position as i6h.22m.-26°io' 

DO. 



A fine binary star, with a period, according to Doberck, of 234 years. The \ ophiuchi. 
magnitudes are 4£, 5h; and the smaller star is greenish or bluish. According to 16h - 25m - +2°i5' 
Leavenworth (1888) the position is 42°"6, and distance 1"'55. 

A notable binary star. Duner makes the period 35 years. The magnitudes £ Herculis 
are 3, 6j; and in 1888, Schiaparelli makes the position-angle 79°'4, and the i6h.37m.+3i°49' 
distance 1""55. 

The renowned globular cluster in Hercules. This is the most important cluster h 4230 

object of its class, and is indeed one of the chief beauties of the starry heavens. Hercules. 

It consists of thousands of stars, so close together, that in the central parts the ' m 6. 
rays commingle so that the separate stars cannot be made out. 

A bright cluster of stars, but a powerful telescope is required to do it justice. cl *j s * e . r ** 4256 

16h. 51m. -3° 56' 
62. 

A fine pair of 4th and 4*5th magnitudes. According to Dembowski, in 1877, „ D raconis 
the position-angle was 169° *9, and the distance 2" "5. i7h. 3m.+54° 38' 

56. 

This is one of the very finest coloured pairs. The magnitudes are 3'5, 5*5 ; a Herculis. 
the large star being orange, and the small one blue ; apparently stationary. The 17h - 9m - + 14 ° 32 ' 
position and distance given by Webb are 118°*7 and 4" , 5, respectively. 



56 



INTRODUCTION. 



i:if ?S°S"- %n Stnrre gives magnitudes as 4. 5*L The smaller star is a pale blue ;. and 

sa " ~° Webb gives position-angle 308°"9, and distance 2fl. 

XebuiaH4373 One of the best examples of those extraordinary objects, the Planetary 

i:h.59m.^66 r 3S' Nebulae. Huggins finds it to be composed of gaseous materials. 

51, 56, 57. 

NebnJaH4403 This is one of the nebulae that can be observed with comparatively small 

ish.i4m.-i6 r i5' optical power. The nebula is known as the '"Horse Shoe." Huggins has shown 
it to be gaseous. 

Cluster h 4406 Cluster visible in a moderate instrument, but not a remarkable object. 

Sagittarius. ' J 

15h.l7m.- 24*55' 
62, 69. 

a Lyra?. Vega, a white, first magnitude star, shown by Huggins to have a vast 

i&h.33ni.-j-3ff'4ff atmosphere of hydrogen. There is a companion at 46": position-ande 151 : 9 
(Knott). 

£ Lyr f' „ One °f the most interesting stellar objects. It is a double star with 

57.' components about 3' apart, resolvable with the naked eye. A telescope of 3 

inches aperture will show that each of the stars is itself a double, about 2" or 3'' 
distance. The whole four are doubtless physically connected. 

Lyra The marvellous ring nebula in Lyra. It is easy to fin I, and no great optical 

lsh.^m.-^oS' power is required to show the structure of this most interesting object. 

17 Lyra?. £ cr 00C | illustration of a coloured pair with verv unequal components. The 

19h. 3rn. -32' 19' . % . , . . %. . . " * * * 

57. magnitudes are 6. 11, the larger being yellow, and the smaller blue. 

tS CygnL Q ne f ffe mo $x beautiful stellar objects, fortunately within the reach of verv 

- - gg m j-27'42' o ■ l 

31. " moderate ins trimients, both by reason of the brightness of the components; and 
the distance at which they are separated. The larger star, 3rd magnitude., is 
topaz coloured, and the smaller 7th magnitude, a beautiful blue. The position- 
angle and distance are 55" "6 : 34" '4 (TTebb\ 

i9h nmSiW Magnitudes 3 5 and 9, the smaller star is greenish, but the object is rather 

57. difficult for small instruments. DembowsM (1S77) gives position-angle 330"'], and 

distance l"'6. 

v Aquiia?. A good test object for a small telescope. The stars are 6, 6 "8 magnitudes 

19h.43m.-fll 8 31' /0 , ? , ,, 3. . ..„._ 

62. (Struve), and the distance 1 5. 

t Draconis.^ A fine pair. Magnitudes 4. 7'6. Position-angle 361 ?, 4; distance 2""9 ; (Hall), 

' si, 57. 1877. The smaller star is a fine blue. 

X vSpeSii 532 Tne famous Dumb-Bell Nebula. This is one of the finest objects of its class. 

i9h. 54m. -22-23' There are nianv stars in the field, but Hoggins shows the nebula itself to be gaseous. 

57, 62. 

20h Sm^yi-y '^ ea? >" double star. Magnitudes. 4, 5 ; ll"-8 apart. Position-angle 273 c, 3. 

63. ' The colours are different, the larger being yellowish, and the smaller with a bluish 

tinge. 



INTRODUCTION. 57 

A notable object, especially as being the first star of which the distance was 61 c y"^\ , 
determined. The magnitudes are 5 "3, 5*9, and the position-angle and distance, as ' ' 57. 
determined by Schiaparelli, are 121°'0, 20 ,/, 58 (1888). 

This is a very close and difficult object, interesting as being one of the most o Equuiei. 
rapidly revolving binaries. Magnitudes U 2i 5 ; distance 0"'25. 21h - 9m 63 + 9 ° 31 ' 

A fine cluster of stars belonging to the globular type, of which that in Cluster h 4670 

Pegasus. 

Hercules is the best known example. 2ih.2-im.+ii°3S' 

63. 



star 



A round nebula, which with sufficient power seems to be composed of minute Nebula h 4678 

Aquarius. 
5 - 21h. 27m. -1°22' 

63. 



A triple star, the largest of which, 5th magnitude, is white, and the others, of v- Cygni. 

21h 39m + 2812' 

the 6th and 7*5th magnitudes, are blue. ' 57. 

This is the Garnet Sidus of Herschel, which seems the reddest star visible to ^ Cephei. 

,1 -. , . ,, , 21h. 40m. + 5814' 

the naked eye in the heavens. 57. 

A coloured double. Magnitudes 4*7, 6"5 ; position-angle 284° *8, distance 6"*6, S Cephei. 

22h. Om + 64° 3' 

(Gledhill, 1874). Duner records the colours as pale green and purple, 1879. ' 52J 57. 

A well-known and striking double star. Easy to find in the centre of a £ Aquavii. 

22h. 23m. — 0°38 

triangle of naked eye stars. The magnitudes are 4, 4 ; position 325 Q, 8 ; Distance 63. 

3"'08 (1889), Leavenworth. 

A fine double star. 5 '4 and 7 '5 magnitudes ; large star white, smaller blue. G Cassiopeia. f 
The position and distance are 323° '7, 3" (Webb). " 52'. 



END OF INTRODUCTION. 



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Balls Atlas ofAstrono 



COMET OF COGGIA 1874 







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Key Map. 



THE MOON— 3rd Day. 



To face Plate 27. 



25. Boussingault. 

22. Ponticoulaut. 
19. Frzunlwfer. 



14. Fumerius. 

12. IF. Humboldt. 
7. Petavius. 



I"' Bar 




II. 


Legendre. 


J- 


Hecatcsus. 


3- 


Vendelinus. 


1. 


T'-cnus. 


2. 


Kdstner. 


136. 


Apollcnius 


-J"- 


Firmicus. 


139- 


Xeper. 


140. 


Condorcet. 


!5 2 - 


Picard. 


I 5 I - 


Alhazen. 


if3- 


Peirce. 


167. 


Ckomedes. 


169. 


Burckhardt. 


J 73- 


Geininus. 


172. 


Gauss. 


I7S 


Messala. 


1 So. 


Mercurius. 


188. 


Endymion. 



A Mil re Crisium. 

B Fcuundiialis. 

C Australe. 

D Humboldtianum. 



Balls Atlas of Astro no my 



3* D DAY 



Plate 27. 




Key Map. 



THE MOON-4th Day. 



To face Plate 28. 



26. Boguslaivsky. 
2 c. Boussinga ult. 



22. Pontdcoulant. 



49. Rosenberger. 
46. Janssen. 
45. Fabricius. 



■i n :J)< 







z*C 









A Mare Crisium. 

B , , Faecunditaiis. 

C ,, A us t rale. 

D ,, Humboldlianum. 



V Palus Soinnii. 



44- 


Melius. 


14- 


Furnerius. 


r S 


Stevinus. 


43- 


Neander. 


41. 


Reichenbach 


16. 


Snellius. 


7- 


Petavius. 


56. 


Sanibech. 


34- 


Colombo. 


3- 


Vendelinus. 


3 1 - 


Godenius. 


32- 


Gutteviberg. 


1. 


Langrenus. 


3°- 


Lubbock. 


29. 


Messier. 


J 55- 


Secchi. 


i 3 5. 


Apollonius. 


154- 


Tariuiiius. 


!5 2 - 


Picard. 


153- 


Peirce. 


*5 6 - 


Proclus. 


166. 


Macrobius. 


167. 


Cleomedes. 


i 5 3. 


J arisen. 


172. 


Gauss. 


176. 


Berzelius. 


175- 


Messala. 


181. 


Franklin. 


185. 


Chevallier. 


186. 


Atlas. 


180. 


Mercurius. 


188. 


Endymion. 


189. 


De la Rue. 



g. Pyrenees Mis. 



LaliIs Atlas ofAstrono 



-f™ DAY 



Plate 28. 







Key Map. 



THE MOON-5th Day. 



To face Plate 29. 



27. Schomberger. 
54. Manzinus. 
53. Mutus. 



49. Rosenberger. 
48. Vlacq. 
52. Pitiscus. 



5* Bay 




46. 


Janssen. 


45- 


Fabricius. 


44- 


Melius. 


14- 


Fur?:-: 


64. 


Siiborius. 


63. 


Piccolomini. 


62. 


Fracasiorius 


36. 


S an f bee A. 


7 • 


Petavius. 


3- 


Vendelinus. 


3i- 


Godcnius. 


32- 


Guttemberg. 


1. 


Langrenus. 


58. 


Isidorus. 


57- 


Cape I la. 


29. 


Messier. 


159. 


Vitru i 


160. 


Maraldi. 


220. 


Le Monnier. 


219. 


Chacornac. 


218. 


Posidonius. 


214. 


Plana. 


187. 


Hercules. 


180. 


Atlas. 


188. 


Endymion. 


189. 


De la Rue. 


198. 


Euctemon. 



A Mare Crisium. 

B , , Fcecunditalis. 

E ,, Tranquillitatis. 

F ,, Nectaris. 



D Mare Humboldtianum. 
G Lac us Somniorum. 
H ,, Mortis. 



g. The Pyrenees. 
k. Taurus Mts. 



5P* DAY 



Hate.29. 




Key Map. 



THE MOON-6th Day. 



To face Plate 30. 



126. Bacon. 

121. Maurolycus. 



6 ^Dav 



71. Buck. 

64. Stiborius. 

65. Riccius. 




/ t? 






, 700 tff 2 



62 O )V A 30 

i -9j F ° F 6»* 
S °°) J op" 

<' \ 1 k 







t 

0*50 A 

022^/ 




66. 


Rabbi Levi. 


67. 


Zagut. 


63- 


Piccolomini. 


93- 


Pons. 


62. 


Fracastorius. 


90. 


Sacrobosco. 


91. 


Format. 


81. 


Catharina. 


82. 


Tacitus. 


80. 


Cyrillus. 


59- 


Mddler. 


79- 


Theophilus. 


72. 


Hypatia. 


247. 


Sabine. 


246. 


Ritter. 


250. 


Arago. 


229. 


Mac lea r. 


228. 


Ross. 


227. 


PI in ius. 


226. 


Dawes. 


256. 


Bessel. 


220. 


Le Monnier. 


219. 


Chacomac. 


2l3. 


Posidonius. 


208. 


Eudoxus. 


207. 


Arisioteles, 


197- 


Melon. 


202. 


Scoresby. 



A Mare Crisium. 
B . , Fcecunditatis. 
D ,, Humboldtianum. 
E M Tranquillitatis. 



F Marc Xcctaris. 

G Lacus Somniorum. 
H ,, Mortis. 

J Mare Serenitaiis. 



g. The Pyrenees. 

h. Altai Mts. 

k. Taurus Mis. 

s. Mt. Argceus. 



Ball's Atlas ofAstrono 



6T M DAY 



Plate 30 




^e~ Vsr 



rzz v: ;::-t:z zi- 



_; face -Lite 31 



z : z '- ■':::.;. 
zz: I zz':. 



zz - A'z: ■ z: \ 




B , , F&cicniita&s. 



K Frigmris. 

M „ Vrnf m rnm. 
J ,. Serauiatis. 



: : : i"; ..; f ; -. 

::; 7z-~.z~.: ;..:. 

'-"■ A .': zz:z;:z. 

:.: I : V ' ■■: :' - 

:c A.z: z-.:..: 

::: ?.z_Az:- 

::: i"."_: -.' ':; -l.\ 

: : f _ . - •■; j;; 

86. Aimummu 

in: _-:.? :.-:'_.--:;l.\ 

: : : _~~; - /. 

hi. HaJOej. 

::: .V; -_.-.: -v ::-.-. 

113. H&rrvcks. 

::_ .".;:•;.:.;. 

: - ; 

-_j_ A 



231. Jm&ms Gsmr. 

Z-: /_"-;;.";:.;. 

-: : - z z...:z 

234. Memeiams. 

235. Sm^idms Gattms. 
237. limmf. 

257. Tie^eiws. 

2-J&. CoMffiKS. 

20: A^i:::z-:Siz 

208. Emdaxms. 

zrz- A. -:z:::-z'.iz. 

H Lmcms Mortis. 

x =--:--■ - 

M .If-'v ~~z:z~. —,. 
b. Tie Camcasws. 
L The Hcmms Mis. 
k. Tie Tamrms Mis. 



Ball's Atlas of Astronomy. 



7T» DAY 



Plate 31. 




Key Map. 



THE MOON-8th Day. 



To face Plate 32 



300. Moretus. 
297. Deluc. 
296. Maginus, 



8™Da$> 



290. Saussure. 
116. Walter. 
285. Ball. 




P Sinus Medii. 

M , , Aistuum. 

J Mare Serenitatis. 

L ,, Imbrium. 



X Palus Nebularzitn. 
Z , , Putredinis. 
K Mare Frigoris. 



278. 


Regiornontatius. 


277. 


Purbach. 


274. 


Thebit. 


266. 


Arzachel. 


267. 


A Ipetragius. 


265. 


Alphonsas. 


264. 


Ptolemceus. 


263. 


Herschel. 


261. 


Mosting. 


373- 


Sommering. 


374- 


Schroter. 


375- 


Pallas. 


260. 


Autolycus. 


399- 


Archimedes. 


257- 


ThecBtetus. 


259- 


Aristillus. 


258. 


Cassini. 


211. 


Great Alpine Valley 


4*3- 


Plato. 


414. 


Timceus. 


416. 


Epigenes. 


417. 


Goldschmidt. 



a. The Alps. 

b. The Caticasus. 

c. The Apennines. 



Ball's Atlas o f Astron* 



3™ DAY 



Plate 3£ 




S.t7 ^- r i? 



THE MOON-9tli Day. 



To face Plate 3a 



300. Moreius. 
2gg. Cysatus. 
298. Clavius. 



296. Magimms. 

294. LoKgoammfamus. 

z : : Tycka. 



- Dax 




— ■ 



_ : 1 




■" r« 

. 1 -: : - 



- 

w - 

•Um ■-■'■ 



293- 


Wintelm I. 


_:_ 


sir. 1 :::-.:. 


; :;. 




283. 


' "".'.'-.:•"•.:.'../"•. 


2S0. 




= :: 


sz-:.:i: ''..:. 


275- 


5j 


: 




;■- 


~ 


2 _ : 




: '.- 




-:"„- 


.-J / : •:::.; 


--- 


_ r .-;.";■ -:,r-.. ■ 


ZJO. 




271. 


Parry. 


37a 


I : ■: : '.i -.:' 


262. 


Lz'.-.i •::'■: 


-\ 




:"- 


- 


:"" 


.= .:■::;"• 


5-: 


S :.::'::>: 


?••: 


Copernicus. 


:'--■ 


— • ' \ '."" . :'. 


71 


~.:_. 1 .:::.-. 


--5 




_l:: 


7:-:.\- :;-;;. 


_:: 


I,:--V:' -". 


f? : 


.-.-:'.: :■:£■{:. 


- : _ : 


?:■:.. 


--; 


7. ■-.:■-.:. ".-:. 


-"-• 


?:.'.:: ;;.;';. 


j.::. 


A -. :..'.: j" ; ".:.'. 



K 3iar« Frzgoris. 
L , , Imirium. 
N Simms .-Estuum. 



3/~« - 1 ' 



a. 7"^ ^./.\ 

b. The Caucasus Mts, 



Ball's Atlas ofAstronc 



37? DAY. 



Plate 33 




Key Map. 



THE MOON— 10th Day. 



To face Plate 34. 



302. Newton. 

312. Blancanus. 

313. Scheiner. 



10 ^D cry 



K Mare Frigoris. 
L , , Imbrium. 

P Sinus Medii. 

Q Mare Ntibium. 

R Sinus Iridum. 



2.9%. Clavius. 

315. Rost. 

294. Longomontanus. 




p °yy, 



C-3 26 



Q, ooa 1 ^ 



Ji 



e»37/> 




a. The Alps. 

b. 7^£ Caucasus. 

c. 7^ Apennines. 

d. 7^£ Carpathians. 
q. /Y«>. 



291. 

293- 

292. 

326. 

338. 

337- 

355- 

339- 

34°- 

34i- 

345- 

34 2 - 

343- 

370. 

37i- 

377- 

380. 

384 
383- 
403- 
402. 
404. 
401. 

399- 
407. 
409. 
410. 
4*3- 
423- 
419. 
420. 



Tycho. 
Wilhelm I. 
Heinsucs. 
Hainzei. 
Cichus. 
Caption us. 
Ramsden. 
Mercator. 

nus. 
Kies. 
Hippalus. 
Bullialdus. 
Lubiniezky. 
Euclides. 
Land sb erg. 
Reinhold. 

Copernicus. 

Tobias Mayer. 

Gay Lussac. 

Pytheas. 

Lambert. 

Euier. 

Timocharis. 

Archimedes. 

Caroline Herschel. 

Leverrier. 

Helicon. 

Plato. 

Condamine. 

Font 'ene lie. 

Philolaus. 



r. Pi ton. 

u. Prom Laplace. 



BaliIs Atlas or Astronomy. 



10 T* DAY 



Plate .34. 




Key Map. 



THE MOON- 11th Day. 



To face Plate 35. 



305. Casatus. 

306. Klaproth. 

307. Wilson. 

H^Day 



309. Bettinus. 
311. Segner. 
313. Scheiner. 




L Mare Imbrium. 
K „ Frigoris. 
Q „ Nubium. 
R Sinus Iridum. 
S Oceanus Procellarum. 
Mare Humorum. 



a. The Alps. 

b. 7^* Caucasus. 

c. 77z<? Apennines. 

d. 7Vz£ Carpathians. 

e. 77*6' Sinus Iridum Highlands. 



317. 
318. 



355 
335 
334 



298. Clavius. 
315. tfarf. 

Schiller. 

Bayer. 
326. Hainzel. 
337. Capuanus. 

Rams den. 

Vitello. 

Lee. 
333. Doppelrnayer. 

345. Hippahis. 

346. Agatharchides. 

347. Gassendi. 

348. Herigonius. 

349. Letronne. 

370. Euclides. 
369. Wichmann. 
368. Flamsteed. 

371. Landsberg. 

385. Kunowsky. 

377. Reinhold. 

386. Encke. 

378. Hortensius. 

387. Kepler. 
380. Copernicus. 

379. Milichitcs. 
384. Tobias Mayer. 
383. Gay Lussac. 

404. Euler. 
402. Lambert. 
401. Timocharis. 
399. Archimedes. 

405. Diophantus. 

406. Delis le. 
451. Gruithuisen. 
427. Mairan. 
426. Sharp. 

425. Bianchini. 
423. Condamine. 
413. Plato. 

429. Harpalus. 

430. J.F.W.Herschel. 

420. Philolaus. 

421. Anaximenes. 
i. Riph&an Mts. 
q. PzVo. 

r. Piton Mountain. 
u. Prom Laplace. 



BaliIs Atlas of Astronomy. 



I J I" DAY, 



Plate 35. 




Key Map. 



THE MOON-12th Day. 



To face Plate 36. 



317. Schiller. 

318. Bayer. 
321. Phocylides. 

12* Day 



323. Schickard. 
327. Lehmann. 
332. Vieta. 




W /I03S9 
()356\ 

Of' °^ 



(j 339 



4449 




351- 

350- 

347- 
359- 
356. 
357- 
349- 
368. 
386. 
389- 
387- 
39°- 
447- 
448. 

404. 

449- 
427. 
426. 
425- 
423- 
419. 

43* ■ 
420. 

421. 



Cavendish. 
Mersenius. 
Gassendi. 
Fontana. 
Billy. 
Hans teen. 
Letronne. 
Flams teed. 
Encke. 
Reiner. 
Kepler. 
Marius. 
Aristarchus. 
Herodotus. 
Euler. 
Wollaston. 
Mairan. 
Sharp. 
Bianchini. 
Condamine. 
Fontenelle. 
Anaximander. 
Philolaus. 
Anaximenes. 



K Mare Frigoris. 
L , , Imbrium. 

Q Mare Nullum. 



S Oceanus Procellarum. 
Mare Humorum. 



e. The Sinus Iridum 

Highlands. 
u. Prom. Laplace. 



ialls Atlas of Astronomy 



\Z TH DAY , 



Plate 36 




Key Map. 



THE MOON— 13th Day. 



To face Plate 37. 



321. Phocylides. 

322. Wargentin. 
325. Inghirami. 

13^ Day 



L Mare Imbrium. 
Q ,, Nubium. 
R Sinus h'7 



323. Schickard. 

329. Pia 1 

330. Lagrange. 




332. Vieia. 

351. " Cavendish. 

35a Merser. 1 

359. Fontana. 

361. Criigcr. 

362. Rocca. 

363. Grimaldi. 
366. Lohrmann, 

391. HeveL 

392. Cavaicrius. 
397. Seleucus. 
448. Herodotus. 
447. Aristarchus. 
445. 5rygx. 
432. Pythagoras. 



S Ocean us Proccllarum. 
f Mare Humorum. 
W Sinus Ports. 



e. TA£ Sinus Iridum 

Highlands, 
•a. Prom. Laplace. 



Ialls Atlas of Astrono 



13™ DAY. • 



Plate 37. 




Key Map. 



THE MOON-14th Day. 



To face Plate 38. 



316. Bailly. 

321. Phocylides. 

322. Wargentin. 



325. Inghirami. 
323. Schickard. 
329. Piazzi. 








K Mare Frigoris. 
L 1 » Imbriuyn. 
R Sinus Iridum. 



S Oceanus Procellarum. 
T Mare Humorum. 
W Sinus Roris. 



33°- 


Lagrange. 


353- 


Eichstddt. 


362. 


Rocca. 


363- 


Grimaldi. 


365. 


Riccioli. 


366. 


Lohrmann. 


39i- 


Hevel. 


392. 


Cavalerius. 


393- 


Olbers. 


394- 


Cardatius. 


395- 


Krafft. 


448. 


Herodotus. 


447- 


Aristarchus. 


397- 


Seleucus. 


445- 


Briggs. 


446. 


Otto Struve. 


439- 


Repsold. 


438. 


Xenophanes. 


437- 


Cleostratus. 


43 2 - 


Pythagoras. 



BaliIs Atlas of Astronomy. 



(4 TH DAY 



Plate 38. 




ialls Atlas ofAstronomy. 



Plate 39 



bi 



J curt? Mi.An.igni. 

Feb? 10. P.M. 
March 8. P.M. 

April Daylight 
May 
June 



January MidmgLu 

and also as follows 



July JJa^luf/i^ 



Aug 1 
Sept V 
Oct r 6. 


AM 


No^r 4- 


AM 


d&c 1 : 2 


A.M 




South 
or at SidercaLTime 7* 1 37" 






Ball's Atlas of Astronomy. 



Plate 40. 



Jan.? Z.A.M. 
Feb? Midnight 
March 10.P. M. 



February Midnight 

and also as follows 



Ju ly D ay Ivaht 
Axuj* 

Oct r 

Kov r 6. A.M. 

J?er. r 4, A.M. 




South 
or at Sidereal Time 9'. J 37 m 






I ails Atlas o f Astro noi 



PlaLe4l 



Jan " -1. A.M 
Feb? 2. A.M. 

Mru-c/i Jn.tln.iqht 
April 10. P M. 
M<iy 8 . P. K 
June DonjJiqlxt 



Marcli Mi.cLii£lit 

CLnd al^o as Pollens 



llJUOy 




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— 03 



South 
or at Sidereal Time ll h 37™ 



Ball's Atlas of Astronomy. 



Plate 42 



Jan? 6, A.M. 
Feb? 4, A.M. 

March 2, A.M. 
April Midnight 
May 10. J 3 . M. 
•Tune Daylight 



April Midnight 

and also as follows 

1 



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Oct. r 






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• • • 



Ball's Atlas of Astronoi 



Plate 43 




BaliIs Atlas o f Astronomy. 



J.tm.y DavU-ght 
Fe£? 

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June Midnight 

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and also as follows 



Plate 41 



IffUOrf 



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South 



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* # 



Ball's Atlas of Astronom 



Plate 45 




Ball's Atlas of Astronomy. 



Plate 46 



' 



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Auy, Miclruakt 

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No v r G, P. M. 
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South 
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Ball's Atlas of Astronomy. 



Plate +7 



September Mi An igkt 

and also as follows 



Ifi-LOft 



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L_ 



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Ball's Atlas of Astronomy. 



PI axe 42 



Jcurt y 6. P. M 

Feb? Daylight 

Maruh 

April. 

May 

June 



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and. also as follows 



J-llLv Daylzqlit 

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Deer S.F.M 



ft 

Co 







South 
op At Sidereal Time I 1 ? .37™ 



Ball's Atlas of Astronomy. 



PI ate .49 



Jan? 8. P.M. 

Feb? 6, P.M. 

Mrxroh Dayhaht 

April 

May 

June. ,. 



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Oct! Z.A.M. 

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South 
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Ball's Atlas of Astronomy, 



Plate 50 




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Balls Atlas of Astronomy 



NORTHERN INDEX MAP 



Plate 71 




Salls Atlas of Astronomy. 



SOUTHERN INpEX MAP 



Plate 72 . 




INDEX. 



INDEX. 



PAGE 

Archimedes, Lunar Object No. 399, PI. 24, 32, 

33,34,35 28 

Aechytas, Lunar Object No. 206, PI. 23 27 

Arcturus or a Boons, PI. 55, 56, 61 54 

Arg^us, Lunar Mountain, PI. 30 ... 29 

Argelander, Durchmusterung Atlas 39 

Argelander, Star Catalogue 40 

Argelander, Magnitudes of the Pleiades 10 

Argelander, Lunar Object No. 107, PI. 26...... 26 

Argus, r), Variable Star 42 

ARiADiEUS, Lunar Object No. 251, PI. 23 27 

Ariel, Satellite of Uranus, PI. 6 6 

Aries, PI. 52, 53, 58, 71, 72 3 

Arietis, y, a Double Star, PI. 58 47 

Arietis, 41, a Quadruple Star, PI. 53 49 

Aristarchus, Lunar Object No. 447, PI. 24, 36, 

37,38 29 

Aristillus, Lunar Object No. 259, PI. 23, 32, 33 27 
Aristoteles, Lunar Object No. 207, PI. 23, 30, 

31 27 

Arnold, Lunar Object No. 194, PI. 23 27 

Arzachel, Lunar Object No. 266, PI. 25, 32, 33 27 

Ascending Node of Planetary Orbit 3 

Asteroids, PI. 3 3 

Astronomical Symbols 3 

Atlas, Lunar Object No. 186, PI. 23, 28, 29, 30 27 
Auriga, PI. 53, 54, 71. 

Auriga, Cluster in, H 1067, PL 53 50 

Auriga, Cluster in, H 1119, PL 53 50 

Auriga, Cluster in, H 1295, PL 53, 54 51 

Auriga, £, irregularly Variable Star 41 

Australe, Mare, in Moon, PI. 26, 27, 28 29 

Autolychus, Lunar Obj ect No. 260, PL 23, 32, 33 27 

Axis Major of Elliptic Orbit 2 

Axis Minor of Elliptic Orbit 2 

Axis, Polar, PL 1. 

Azimuth. — The angle between a point on the 

horizon and the north or south. 

Azophi, Lunar Object No. 89, PL 26 26 

Azout, Lunar Object No. 138, PL 23 26 

Babbage, Lunar Object No. 434, PL 24 ..- 28 

Bacon, Lunar Object No. 126, PL 26, 30 26 

Bailly, Lunar Object No. 316, PL 25, 38 28 

Baily, Lunar Object No. 216, PL 23 27 

Ball, Lunar Object No. 285, PL 25, 32 27 

Banks Cape, on Mars, PL 9. 

Barocius, Lunar Object No. 122, PL 26 26 

Barrow, Lunar Object No. 203, PL 23 27 

Bayer, Lunar Object No. 318, PL 25, 35, 36 ... 28 

Beaumont, Lunar Object No. 83, PL 26 26 



PAGE 

Beer Continent, on Mars, PL 9. 

Beer, Lunar Object No. 400, PL 24 28 

Behaim, Lunar Object No. 141 27 

Behrmann, Star Magnitudes 40 

Bell, Mr. J. Hind. See Preface. 

Bellot, Lunar Object No. 39, PL 26 • 26 

Bernouilli, Lunar Object No. 174, PL 23 27 

Berosus, Lunar Object No. 171, PL 23 27 

Berzelius, Lunar Object No. 176, PL 23, 28 ... 27 

Bessarion, Lunar Object No. 388, PL 24 28 

Bessel, Positions of the Pleiades 10 

Bessel, Lunar Object No. 236, PL 23, 30 27 

Bettinus, Lunar Object No. 309, PL 25, 35 28 

Bianchini, Lunar Object No. 425, PL 24, 35, 36 28 

Biela, Lunar Object No. 23, PL 26 26 

Biela's Comet, Orbit of, and of Meteors of 

November 27th, PL 2, 3 3 

Billy, Lunar Object No. 356, PL 25, 36 28 

Binary Star.— A Double Star whereof the two 

components are found to be revolving 

around each other. 

Binary Star, Orbit of a, PL 13 12 

Birmingham, Lunar Object No. 415, PL 24 28 

Birt, Lunar Object No. 276, PL 25 27 

Blancanus, Lunar Object No. 312, PL 25, 34... 28 

Blanchinus, Lunar Object No. 101, PL 26, 31... 26 

Bode, Lunar Object No. 376, PL 24 28 

Boguslawsky, Lunar Object No. 26, PL 26, 28 26 

Bohnenberger, Lunar Object No. 60, PL 26 ... 26 

Bond, G. P., Drawing of Comet of Donati, PL 15 16 

Bond, C. P., Lunar Object No. 222, PL 23 27 

Bond, W. C, Lunar Object No. 204, PL 23 27 

Bootes, PL 55, 56, 61, 71. 

Bootis, a, or Arcturus, PL 55, 56, 61 54 

Boons £, a Double Star, PL 61 55 

Bootis e, a Double Star, PL 56 55 

Bootis £, a Double Star, PL 61 55 

Bootis 44, a Double Star, PL 56 55 

Bjnpland, Lunar Object No. 272, PL 25, 33 ... 27 

Borda, Lunar Object No. 40, PL 26 26 

Boscovich, Lunar Object No. 232, PL 23, 31 ... 27 
Boussingault, Lunar Object No. 25, PL 26, 27, 

28 26 

Bradley, Lunar Mountain, PL 23 29 

Brayley, Lunar Object No. 452, PL 24 29 

Bredichin's Theory of Comets' Tails, PL 10 ..9, 16 

Brett, View of Mars by 9 

Briggs, Lunar Object No. 445, PL 24, 37, 38 ... 29 
Browning Land, on Mars, PL 9. 

Brunnow's Spherical Astronomy 10 

Buch, Lunar Object No. 71, PL 26, 30 26 



INDEX. 



PAGE 

Bullialdus, Lunar Object No. 342, PI. 25, 34 28 

Burckhardt Land, on Mars, PI. 9. 

Burckhardt, Lunar Object No. 169, PL 23, 27 27 

Bureau des Longitudes— Annuaire du 40 

Burg, Lunar Object No. 215, PL 23 27 

Burton Bay, on Mars, PL 9 9 

Busching, Lunar Object No. 70, PL 26, 30 26 

Byrgius, Lunar Object No. 352, PL 25 28 

Cabeus, Lunar Object No. 304, PL 25 28 

Calippus, Lunar Object No. 256, PL 23, 31, 32 27 
Camelopardalis, PL 51, 53, 54. 

Camelopardalis, 7, Double Star, PL 53 50 

Campanus, Lunar Object No. 340, PL 25, 34 ... 28 

Cancer, PL 54, 59, 60 3 

Cancer, Cluster H 1712 in, PL 60 52 

Cancer, Tropic of, PL 15. 

Cancri, £, Multiple Star 52 

Cancri, 11, a Double Star, PL 54 52 

Canes Venatici, PL 55, 56. 

Canes Venatici, Nebula H 3572 in, PL 55 54 

Canes Venatici, Nebula H 3636 in, PI. 55 54 

Canis Major, PL 59, 66, 71, 72. 

Canis Majoris or, or Sirius, PL 59 51 

Canis Minor, PL 59, 72. 

Canis Minoris S., regularly Variable Star 41 

Capella, or a Auriga, PL 53. 

Capella, Lunar Object No. 57, PI. 26, 29 26 

Capricorn, Tropic of, PL 15. 

Capricornus, PL 63, 69, 71, 72 3 

Capuanus, Lunar Object No. 337, PL 25, 34, 35 28 

Cardanus, Lunar Object No. 394, PL 24, 38 ... 28 
Carina, PL 66, 67, 70. 

Carina, I, regularly Variable Star 41 

Carina, R, regularly Variable Star 41 

Carina, S, irregularly Variable Star, PL 67 ... 42 

Carlini, Lunar Object No. 408, PL 24, 34 28 

Carpathians, Lunar Mountains, PL 24, 34, 35 29 

Carrington, Longitudes of Sun Spots 19 

Casatus, Lunar Object No. 305, PL 25, 35 28 

Cassini Land, on Mars, PL 9. 

Cassini, Lunar Object No. 258, PL 23, 32 27 

Cassini, J. J., Lunar Object No. 422, PL 24, 32 28 

Cassiopeia, PL 51, 52, 53, 71. 

Cassiopeia, R, regularly Variable Star, PL 52 41 

Cassiopeia, rj, Double Star, PL 52 47 

Cassiopeia, t, Triple Star, PL 52, 53 48 

Cassiopeia, <t, a Double Star 57 

Catharina, Lunar Object No. 81, PL 26, 30 ... 26 



PAGE 

Caucasus, Lunar Mountains, PI. 23, 31, 32, 33, 

34,35 29 

Cauchy, Lunar Object No. 161, PL 23 2f 

Ca Valerius, Lunar Object No. 392, PL 24, 37, 38 28 

Cavendish, Lunar Object No. 351, PL 25, 36, 37 28 

Cayley, Lunar Object No. 254, PL 23 27 

Censorinus, Lunar Object No. 55, PL 26 26 

Centaurus, PL 67, 68, 72. 

Centauri, R, irregularly Variable Star 42 

Central Meridian. — The line joining the north 

point to the south point on one of the 

Monthly Maps in this Atlas. 

Cephei, d, regularly Variable Star, PL 52 41 

Cephei, u, irregularly Variable Star 42, 57 

Cephei, £, a Double Star, PL 52, 57 57 

Cepheus, Lunar Object No. 182, PL 23 27 

Cepheus, PL 51, 52, 57, 71. 

Ceti, T, regularly Variable Star, PI. 63, 64 41 

Ceti, y, a Double Star, PL 58 49 

Ceti, v, a Double Star, PL 58 48 

Ceti, p, regularly Variable Star, PL 58 41 

Ceti, 84, a Double Star, PL 58 49 

Cetus, PL 58, 63, 61, 71, 72. 

Chamaleon, PL 70. 

Chacornac, Lunar Object No. 219, PL 23, 29, 30 27 

Challis, Lunar Object No. 199, PL 23 27 

Charts for Sun Spot Observations, PL 18, 19, 

20,21,22 19 

Chart of Mars, PL 9 , 8 

Chevallier, Lunar Object No. 185, PL 23, 24, 

28 27 

Christian Mayer, Lunar Object No. 205, PL 23 27 
Christie Bay, in Mars, PL 9. 

Cichus, Lunar Object No. 338, PL 25, 34 28 

Circinus, PL 68. 

Circle (Great). — A circle which divides the 

sphere into two equal portions. 

Circles of the Sphere 1 

Clairaut, Lunar Object No. 123, PI. 26, 31 26 

Clausius, Lunar Object No. 336, PL 25 28 

Clavius, Lunar Object No. 298, PL 25, 33, 34, 35 28 

Cleomedes, Lunar Object No. 167, PL 23, 27, 28 27 

Cleostratus, Lunar Object No. 437, PL 24, 38 28 
Close, Rev. M. H. See Preface. 

Clusters (Great) in Perseus, PL 52, 53 48 

Cluster H 1067, in Auriga, PL 53 50 

Cluster H 1119, in Auriga, PL 53 50 

Cluster H 1295, in Auriga, PL 53, 54 51 

Cluster H 1712, in Cancer, PL 60 52 

Cluster H 3900, in Virgo, PL 61 54 



6 



IXDEX. 



PAGE 

Cluster H 4083, in Libra, PI. 61 55 

Cluster H 4280, in Hercules 55 

Cluster H 4256, in Ophiuchus, PI. 62 55 

Cluster H 4406, in Sagittarius, PL 62, 69 56 

Cluster H 4670, in Pegasus, PI. 63 57 

Cluster H 4678, in Aquarius, PI. 63 57 

Ccelum, PI. 65. 

Coggias' Comet, 1874, PI. 16 .... 16 

Colombo, Lunar Object No. 34, PI. 26, 28 26 

Columba, PL 65, 66, 72. 

Coma Beresicis, PL 55, 61. 

Coma Berenicis, H 3321, Nebula in. PL 55, 61 54 

Coma Berenicis, H 3453, Nebula in, PI. 61 54 

Com-E Berenices, 24, a Double Star, PL 61 54 

Comet of Biela, PL 2 3 

Comet of Coggia, 1874. PL 16 16 

Comet of Donati, Oct. 5, 1858, PL 15 16 

Comet of 1882, PL 3 4 

Comet I., 1866, Orbit of, PL 2 3 

Comet III., 1862, Orbit of, PL 2 3 

Comets.— Description of Plates, PL 10. 15, 16. ..9, 16 

Comets' Tails, Bredicbin's Theory of. PL 10 ... 9 
Common, Mr. A. A. See Preface. 

Companion to the Observatory 46 

Comparative Sizes of the Planets, PL 4 4 

Condamixe. Lunar Object No. 423, PL 24, 34, 

35,36 28 

Condorcet, Lunar Object No. 140, PL 23, 27... 27 

C o nical Projection for Star Maps 39 

Conjunction.— Used of two planets when they 

have the same longitude, viewed from the 

Sun. 

Conon, Lunar Obj ect No. 239, PL 23 27 

Cook, Lunar Object No. 35, PL 26 26 

Copeland, Dr. B. See Preface. 

Copernicus, Lunar Object No. 380, PL 24, 33, 

34, 35 24, 28 

Copernicus Land, on Mars, PL 9. 

Cor Caroli, a Double Star 54 

Cordilleras, Lunar Mountains 29 

Corolla, PL 69. 

Corona Borealis, PL 56, 71. 

Corona of Sun, January 1889, PL 17 17 

Corona <r, a Double Star, PL 56 55 

Corona B., irregularly Variable Star, PL 56 ... 42 
Corona T., Nova, 1866, irregularly Variable 

Star, PL 56 42 

Corvus, PL 60, 61, 71, 72. 
Crater, PL 60, 67, 71, 72. 

Crateris y, a Double Star, PL 60 53 



PAGE 

Crisium Mare, Lunar Sea, PL 23, 27, 28, 29, 

30, 31 29 

Crossle Y. — Book on Double Stars 46 

Crozier, Lunar Object No. 38, PL 26 26 

Cruger, Lunar Object No. 361, PL 25, 37 28 

Crux, PL 67, 72. 

Culmination. — The passage of a heavenly body 
across the meridian. 

Curtius, Lunar Object No. 132, PL 26, 31 26 

Curve, Interpolating, PL 13. 

Cuyier, Lunar Object No. 125, PL 26 26 

Cygni, /3, a Double Star, PL 57 56 

Cygni, S, a Double Star, PL 57 56 

Cygni, fx. a Double Star, PL 57 57 

Cygni, %, regularly Variable Star, PL 57 41 

Cygni, 61, a Double Star, PL 57 57 

Cygnus, PL 52, 57, 71. 

Cyrillus, Lunar Object No. 80, PL 26, 30 26 

Cysatus, Lunar Object No. 299, PL 25, 33 23 

D'Alembert Mts., Lunar Object 29 

Daniell, Lunar Object No. 217, PL 23 27 

Damoiseau, Lunar Object No. 364, PL 25 28 

Darby's Astronomical Observer 46 

Davy, Lunar Object No. 269, PL 25 27 

Dawes, Lunar Object No. 226, PL 23, 30 27 

Dawes' Forked Bay, on Mars, PL 9 9 

Dawes' Ocean, on Mars, PL 9. 
Declination. — The angular distance of a celes- 
tial body from the Equator 1 

Deimos, one of the Satellites of Mars, PL 6. 5 

Delambre, Lunar Object No. 73, PL 26 26 

Delambee Sea, in Mars, PL 9. 

De la Bue, Lunar Object No. 189, PL 23, 28, 29 27 

De la Bue Ocean, in Mars, PL 9. 

Delaunay, Lunar Object No. 103, PL 26 26 

Delisle, Lunar Object No. 406, PL 24, 35 28 

De Lottigxez Sea, in Mars, PL 9. 
Delphin, PL 63, 71, 72. 

Delphini, y, a Double Star, PL 63 56 

Deluc, Lunar Object No. 297, PL 25, 32 2S 

Democritus, Lunar Object No. 193, PL 23 27 

De Morgan, Lunar Object No. 253, PL 23 27 

Denning, Position of Meteoric Badiants 42 

Descartes, Lunar Object No. 84. PL 26 26 

Descending Node of Orbit of Planet, PL 2... 3 

De Vico, Lunar Object No. 354, PL 25 28 

Dione, Satellite of Saturn, PL 6 6 

Diontsius, Lunar Object No. 248, PL 23 27 

Diophantus, Lunar Object No. 405, PL 24, 35 . 28 



INDEX. 



PAGE 

Diurnal Parallax , 2 

Doerfel Mountains, Lunar Object 29 

Donati, Lunar Object No. 105, PL 26, 31 26 

Donati's Comet, Oct. 5th, 1858, PI. 15 16 

Doppelmater, Lunar Object No. 333, PI. 25, 35 28 

Dorado, PI. 65, 70, 72. 

Draco, PI. 51, 55, 56, 57, 71. 

Draco, Planetary Nebula H 4373 in, PL 51, 

56, 57 56 

Draconis, e, a Double Star, PL 51, 57 56 

Draconis, /*, a Double Star, PL 56 55 

Drebbel, Lunar Object No. 324, PL 25 28 

Dreyer, Dr. J. L. E.— Quoted about Mars 9 

Dreyer Island, on Mars, PL 9. 

Dumb-bell Nebula, in Vulpecula H 4532 56 

DURCHMUSTERUNG ATLAS 39 

Dusky Ping of Saturn, dimensions of, PL 4... 4 

Earth, Dimensions of and position of Axis, PL 4 4 

Earth, Periodic Time of, PL 2 2 

Earth Eclipsing Moon, PL 7 6 

Earth's Shadow during Eclipse of the Moon, 

PI. 7 6 

Eccentricity of a Planetary Orbit, PL 3 ... 2 

Eclipses, Description of 6 

Eclipse of the Moon, PL 7 6 

Eclipse of the Sun, PL 7 6 

Eclipses of Various Kinds, PI. 7. 

Ecliptic. — The apparent path of the Sun among 

the Stars, PL 1,5 4 

Egede, Lunar Object No. 210, PL 23 27 

EiCHSTaDT, Lunar Object No. 353, PL 25, 38 ... 28 

Einmart, Lunar Object No. 162, PL 23 27 

Electra, in Pleiades, PL 12 10 

Elements.— Used of a Planet's Orbit 2 

Elger, Mr. T. Gwyn. See Preface. 

Elkin, Dr., on the Pleiades 10 

Ellipse.— The form of a Planetary Orbit 2 

Elongation. — The apparent angular distance 

of a body from its centre of motion. 

Enceladus, Satellite of Saturn, PL 6 6 

Encke, Lunar Object No. 386, PL 24, 35, 36 ... 28 

Encke's Comet, PL 3 4 

Endymion, Limar Object No. 188, PL 23, 27, 

28, 29 27 

Epigenes, Lunar Object No. 416, PL 24, 32 28 

Equator (Celestial). — The great Circle midway 

between the Poles. 
Equatorial. — A Telescope mounted so as to 

follow a Star in its apparent daily motion. 



PAGE 

Equinox. — Either of the points on the Equator 
at which the Sun crosses in its annual course 

among the Stars 5 

Equulet, d, a Double Star, PL 63 57 

Equuleus, PL 63. 

Eratosthenes, Lunar Object No. 382, PL 24, 33, 

34 28 

Eridanus, PL 58, 59, 64, 65, 71, 72. 
Euclides, Lunar Object No. 370, PL 25, 34, 35 28 
Euctemon, Lunar Object No. 198, PL 23, 29 ... 27 
Eudoxus, Lunar Object No. 208, PL 23, 30, 31 27 
Euler, Lunar Object No. 404, PL 24, 34, 35, 36 28 

Fabricius, Lunar Object No. 45, PL 26, 28, 29 26 
FACULiE. — Patches on the Sun which are brighter 

thau other parts of the photosphere. 

FiECUNDiTATis Mare, in Moon. PL 27-31 29 

Faraday, Lunar Object No. 120, PL 26 :. 26 

Faye, Lunar Object No. 104, PL 26 26 

Fermat, Lunar Object No. 91, PL 26, 30 26 

Fernelius, Lunar Object No. 118, PL 26, 31 ... 26 

Firmicds, Lunar Object No. 137, PL 23, 27 26 

First Quarter of Moon, PL 7. 

Flammarion Sea, in Mars, PL 9. 

Flamsteed, Lunar Object No. 368, PL 25, 35, 36 28 

Focus. — A point where converging rays meet. 

Fomalhaut, PL 64, 72. 

Fontana, Lunar Object No. 359, PL 25, 36, 37 28 

Fontana Land, on Mars, PL 9. 

Fontenelle, Lunar Object No. 419, PL 24, 33, 

34,36 28 

Fornax, PL 65. 

Foucault, Lunar Object No. 428, PL 24 28 

Fourier, Lunar Object No. 331, PL 25 28 

Fracastorius, Lunar Object No. 62, PL 26, 29, 

30 26 

Fra Mauro, Lunar Object No. 273, PL 25, 33 27 

Frigoris, Mare, in Moon, PL 23, 31-36, 38 29 

Franklin, Lunar Object No. 181, PL 23, 28 ... 27 
Fraunhofer, Lunar Object No. 19, PL 26, 27 26 
Full Moon, PL 7. 
Furnerius, Lunar Object No. 14, PL 26, 27, 28, 

29 26 

Galileo, Lunar Object No. 453, PL 24 29 

Gambart, Lunar Object No. 372, PL 24, 33 28 

Gassendi, Lunar Object No. 347, PL 25, 35, 36 28 

Gartner, Lunar Object No. 192, PL 23 27 

Gauricus, Lunar Object No. 282, PL 25, 33 ... 27 

Gauss, Lunar Object No. 172, PL 23, 27, 28 ... 27 



INDEX. 



Gay Lussac, Lunar Object No. 383, PL 24, 33, 

34,35 28 

Geber, Lunar Object No. 87, PI. 26 26 

Gemini. PI. 54,59,71,72 3 

Gemlnorum, R, regularly Variable Star, PI. 59 41 
Gemlnorum, U, regularly Variable Star, PL 54, 

59 41 

Gemlnorum, a (Castor), a Double Star, PI. 54 52 

Gemlnorum, S, a Double Star, PI. 54, 59 51 

Gemlnorum, r\, regularly Variable Star, PL 54, 

59 41 

Geminorum, k, a Double Star. PI. 54, 59 52 

Gemlnorum, /t, a Double Star, PI. 59 51 

Gemlnorum, K, regiilarly Variable Star, PI. 54, 

59 '. 41 

Geminus, Lunar Object No. 173, PL 23, 27 27 

Gemma Frisius, Lunar Object No. 95, PL 26 ... 26 

Gerard, Lunar Object No. 441, PL 24 29 

Gibbous, Planet when so called 8 

Gill Land, on Mars, PI. 9. 

Gioja, Lunar Object No. 201, PL 23 27 

Glasenapp, Prof., on Orbits of Binary Stars ... 12 

Gledhill, Book on Double Stars 46 

Globular Cluster in Hercules, H 4230, PI. 56 55 

Godenius, Lunar Object No. 31, PL 26, 28, 29 26 

Godin, Lunar Object No. 245, PL 23, 31 27 

Goldschmidt, Lunar Object No. 417, PL 24, 32, 

33 28 

Great Alpine Valley, Lunar Object No. 211, 

PL 23,32 27 

Green's Chart of Mars 8 

Grimaldi, Lunar Object No. 363, PL 25, 37, 38 28 

Grove, Lunar Object No. 212, PL 23 27 

Gruemberger, Lunar Object No. 303, PL 25 ... 28 

Gruithuisen, Lunar Object No. 451, PL 24, 35 29 
Gruithuisen Bay, in Mars, PL 9. 
Grus, PL 64, 69, 72. 

Guerike, Lunar Object No. 270, PL 25, 33 27 

Guttemberg, Lunar Object No. 32, PL 26, 28, 

29 26 

Hadley, Lunar Mountain 29 

LLemus, Lunar Mountain, PL 23, 31, 32 29 

Hagecius, Lunar Object No. 24, PL 26 26 

Hahn, Lunar Object No. 170, PL 23 27 

Hainzel, Lunar Object No. 326, PL 25, 34, 35 28 
Hall Island, on Mars, PL 9. 

Halley, Lunar Object No. Ill, PL 26, 31 26 

Halley's Comet, PL 3 4 

Hanno, Lunar Object No. 143, PL 26 27 



PACE 

Hansen, Lunar Object No. 150, PL 23 27 

Hansen, Lunar Object No. 320, PL 25 28 

Hansteen, Lunar Object No. 357, PL 25, 36 ... 28 

Harbinger Mountains, in Moon, PL 24 29 

Harding, Lunar Obj ect No. 440, PL 24 29 

Harpalus, Lunar Object No. 429, PL 24, 35 ... 28 
Harvard College, Drawings of Comets, PL 15, 

16 16 

Hase, Lunar Object No. 10, PL 26 26 

Heavens, Sphere of the 1 

Hecat^us, Lunar Object No. 5, PL 26, 27 26 

Heinsius, Lunar Object No. 292, PL 25, 33, 34 28 

Heis, Star Catalogue referred to 40 

Helicon, Lunar Object No. 410, PL 24, 34 28 

Heliographic Longitude of the Centre of 

Su^'sDisc 20, 21 

Hell, Lunar Object No. 279, PL 25 27 

Henry, Photographs of Pleiades, PL 12 10 

Hercules, PL 56, 57, 62, 71. 

Hercules, Globular Cluster in, H 4230, PL 56 55 

Hercules, Lunar Object No. 187, PL 23, 29 ... 27 

Hercules S, regularly Variable Star, PL 62 41 

Herculis a, irregularly Variable Star, PL 62... 42 

Herculis n, a Double Star, PL 62 55 

Herculis p, a Double Star, PL 56 56 

Herculis K, a Double Star, PL 56 55 

Hercynian Mountains, in Moon, PL 24 29 

Herigonius, Lunar Object No. 348, PL 25, 35... 28 

Hermann, Lunar Object No. 367, PL 25 28 

Herodotus, Lunar Object No. 448, PL 24, 36, 

37, 38 29 

Herschel, J. F. W., Lunar Object No. 430, PL 

24, 35... 28 

Herschel, W., Lunar Object No. 263, PL 25, 32 27 
Herschel II. Inlet, on Mars, PL 9. 
Herschel I. Continent, on Mars, PL 9. 
Herschel, Caroline, Lunar Object No. 407, 

P1.24, 34 28 

Hesiodus, Lunar Object No. 281, PL 25, 33 27 

Hevel, Lunar Object No. 391, PL 24, 37, 38 ... 28 

Hilda.— One of the Minor Planets, PL 3 3 

Hind, Lunar Object No. 112, PL 26, 31 26 

Hind Peninsula, on Mars, PL 9. 

Hippalus, Lunar Object No. 345, PL 25, 34, 35 28 

Hipparchus, Lunar Object No. 110, PL 26, 31, 32 26 
Htrst Island, on Mars, PL 9. 

Hommel, Lunar Object No. 51, PL 26 ..... 26 

Hooke, Lunar Object No. 177, PL 23 27 

Hooke Sea, on Mars, PL 9. 
Horizon, Rational, PL 1. 
Horizon, Sensible, PL 1. 



INDEX. 



9 



PAGE 

Horologium, PI. 65. 

Horrebow, Lunar Object No. 454, PI. 24 29 

Horrocks, Lunar Object No. 113, PI. 26, 31, 32 26 

Hortensius, Luuar Object No. 378, PI. 24, 35... 28 
Hour Angle. — The angle between the meridian 
and a great circle from the pole to a celes- 
tial body. 

Houzeau, Star Places given by 40 

Huggins, Lunar Object No. 146, PI. 23 27 

Huggins Bay, in Mars, PI. 9 

Humboldt Mountains, Lunar Object 29 

Humboldtianum Mare, in Moon, PI. 23, 27, 28, 

29,30...., 29 

Humboldt, W., Lunar Object No. 12, PI. 26, 27 26 

Humorum Mare, in Moon, PI. 25, 35, 36, 37, 38 29 

Huygens, Lunar Mountains, PI. 23 29 

Hyades, a group in Taurus, PL 71, 72. 

Hydra, PI. 59, 60, 61, 66, 67, 68, 71, 72. 

Hydra, Planetary Nebula in, H 2102, PL 60 ... 53 

Hydr^i R., regularly Variable Star, PL 61 41 

Hydr^i U., regularly Variable Star, PL 60 41 

Hydr.e e, a Double Star, PL 60 52 

Hydrocarbon Tail of Comet, PL 10. 
Hydrogen Tail op Comet, PL 10. 
Hydrus, PI. 64, 65, 70, 72. 

Hyginus, Lunar Object No. 243, PL 23 27 

Hypatia, Lunar Object No. 72, PL 26, 30 26 

Hyperion, Satellite of Saturn. PL 6 6 

Iapetus, Satellite of Saturn, PL 6 6 

Imbrium Mare, in Moon, PL 24, 32-38 29 

Index to Jupiter 36 

Index to Mars . 35 

Index to Saturn 37 

Index to Venus 34 

Indus, PL 64, 69, 70, 72. 

Inferior Conjunction 7 

Inghirami, Lunar Object No. 325, PL 25, 37, 

38 , 28 

Interpolating Curve, for Double Stars, PL 13. 

Iridum Sinus, in Moon, PL 24, 34, 35, 37, 38 ... 29 

Irregularly Variable Stars 41 

Isidorus, Lunar Object No. 58, PL 26, 29 26 

Jacob Land, on Mars, PL 9. 

Jacobi, Lunar Object No. 127, PL 26 26 

Jansex, Lunar Object No. 158, PL 23, 28 27 

Janssen, Lunar Object No. 46, PL 26, 28, 29 ... 26 

Janssen, Photograph of Sun-spot, PL 17 17 

Joynson Sea, in Mars,' PL 9. 



PAGE 

Julius C^isar, Lunar Object No. 231, PL 23, 31 27 

Jupiter, Dimensions of, PI. 4 4 

Jupiter, Drawings of, PL 10 9 

Jupiter, How to find 36 

Jupiter in Opposition 33 

Jupiter, Orbit of, PL 3 3, 4 

Jupiter, Rotation Period of, PL 4. 

Jupiter, Satellites of, PL 6 5 

Kaiser Sea, in Mars, PL 9. 

Kant, Lunar Object No. 78, PL 26 26 

Kastner, Lunar Object No. 2, PL 26, 27 26 

Kepler Land, on Mars, PL 9. 

Kepler, Lunar Object No. 387, PL 24, 35, 36... 28 

Kies, Lunar Object No. 341 , PL 25, 34 28 

Kinau, Lunar Object No. 130, PL 26 26 

Kirch, Lunar Object No. 411, PL 24 28 

Kircher, Lunar Object No. 308, PL 25 28 

Klaproth, Lunar Object No. 306, PL 25, 35 ... 28 

Knobel, Views of Mars 8, 9 

Knobel Sea, an Object on Mars, PL 9. 

Krafft, Lunar Object No. 395, PL 24, 38 28 

Kunowski Land, on Mars, PL 9. 

Kunowsky, Lunar Object No. 385, PI. 24, 35 .. 28 

Lacaille, Lunar Object No. 102, PL 26 26 

Lacerta, PL 52. 

Lacroix, Lunar Object No. 328, PL 25 28 

Lacus Mortis, in Moon, PL 23, 29, 30, 31 29 

Lacus Somniorum, in Moon, PL 23, 29, 30, 31... 29 
Lagrange, Lunar Object No. 330, PL 25, 37, 38 28 
Lagrange Peninsula, on Mars, PL 9. 

Lahire, Lunar Mountain 29 

Lalande, Lunar Object No. 262, PL 25, 33 27 

Lambert, Lunar Object No. 402, PL 24, 33, 34, 

35 28 

Lambert Sea, on Mars, PL 9. 

Landsberg, Lunar Object No. 371, PL 24, 25, 

34,35 28 

Langrenus, Lunar Object No. 1, PL 26, 27, 28, 

29 26 

La Peyrouse, Lunar Object No. 142 27 

Laplace Land, on Mars, PL 9. 

Laplace Promontory, in Moon, PL 24, 34, 35, 

36, 37 29 

Lassell, Lunar Object No. 268, PL 25 27 

Lassell Sea, on Mars, PL 9. 

Last Quarter of Moon, PL 7. 

Latitude. — The angular distance of a heavenly 

body from the Ecliptic. 



10 



INDEX. 



PAGE 

Lavoisier, Lunar Object No. 442, PI . 24 29 

Lee, Lunar Object No. 334, PI, 25, 35 28 

Legendre, Lunar Object No. 11, PL 26, 27 26 

Le Gexttl, Lunar Object No. 144, PL 25 27 

Lehmann, Lunar Object No. 327, PL 25, 36 ... 28 

Leibnitz Mountains, Lunar Object 29 

Le Mooter, Lunar Object No. 220, PL 23, 29, 

30,35 27 

Leo, PL 54, 55, 60, 71, 72 3 

Leo Minor, PL 54, 55. 

Leonids, Shooting Stars, PL 2 3 

Leonis Pi., regularly Variable Star, PL 60 41, 52 

Leonis y, a Double Star, PL 54, 60 53 

Leonis, o, a Double Star, PL 55, 60 53 

Leonis, i, a Double Star, PL 60 53 

Leonis, W, a Double Star, PL 60 52 

Leporis P., regularly Variable Star, PL 59 41 

Lepus, PL 59, 65, 71, 72. 

Letronne, Lunar Object No. 349, PL 25, 35, 36 28 

Leyerrier, Lunar Object No. 409, PL 24, 34 ... 28 

Leterreer Land, in Mars 9 

Lexell, Lunar Object No. 286, PL 25 27 

Libra, PL 61, 62, 68, 71, 72 3 

Libra, Cluster H 4083 in 55 

Librae, c. regularly Variable Star, PL 61 41 

Libratton — The swinging of tbe moon by which 

we can sometimes see a margin beyond the 

half which is commonly directed towards 

us. 

Licetus, Lunar Object No. 124, PL 26, 31 26 

Lichtenberg, Lunar Object No. 444, PL 24 ... 29 

Ltt.ttts, Lunar Object No. 128, PL 26, 31 26 

Lindenau, Lunar Obj ect No. 68, PL 26 26 

Linne, Lunar Obj ect No. 237, PL 23, 31 27 

Littrow, Lunar Object No. 224, PL 23... 27 

Lockyer, View of Mars 9 

Lockyer Island, on Mars, PL 9. 
Lohrmann, Lunar Object No. 366, PL 25, 37, 38 28 
Lohse, Dr. O., on Jupiter. See Preface. 
Longitude. — If a great circle perpendicular to 

the Ecliptic be drawn through any celestial 

body, its longitude is the angle from the 

vernal equinox measured towards the east 

to the foot of the perpendicular. 
Longitude of Perihelion, PL 3. 
Longitude of the Centre of Sun's Disc. 

Heliographic table 20 

Longmans. Messrs. See Preface. 
Longomontanus, Lunar Object No. 294, PL 25, 

33,34 28 



PAGE 

Lubbock, Lunar Object No. 30, PL 26, 28 26 

Lublnieskt, Lunar Object No. 343, PL 25, 34... 28 

Lunar Objects 24 

Lunation. — The period from one new Moon to 

the next. 29-5305879 days. 
Lupus, PL 68, 72. 
Lynx, PL 54. 
Lyra, PL 57, 71. 

Lyra, Annular Nebula H 4447 in, PL 57 56 

Lyr^ 17, a Double Star, PL 57 56 

Lyr.£ a. or Vega, PL 57 56 

Lyr.e f , a Double-double Star, PL 57 56 

Lyr.e /3, regularly Variable Star, PL 57 41 

Maclaurin, Lunar Object No. 4, PL 26 26 

Maclear, Lunar Object No. 229, PI. 23, 30 27 

Macrobius, Lunar Object No. 166, PL 23, 28 ... 27 

Madler, Lunar Object No. 59, PL 26, 30 26 

Madler Continent, on Mars, PL 9. 

Magelhaens, Lunar Object No. 33, PL 26 26 

Maghull Observatory 16 

Maginus, Lunar Object No. 296, PL 25, 32, 33 28 

Maia, in Pleiades 10 

M ain, Lunar Object No. 200, PL 23 27 

Main Sea, in Mars, PL 9. 

Matran, Lunar Object No. 427, PL 24, 35, 36... 28 

Malus, PL 60, 66. 

Mantlius, Lunar Object No. 240, PL 23, 31 ... 27 

Manners, Lunar Object No. 249, PL 23 27 

Manzinus, Lunar Object No. 54, PL 26, 29 26 

Maraldi, Lunar Object No. 160, PL 23, 29 27 

Mar audi Sea, in Mars, PL 9. 

Marco Polo, Lunar Object No. 398, PL 24 28 

Mare Australe, in Moon, PL 26, 27, 28 29 

Mare Crisium, in Moon, PL 23, 27, 28, 29, 30, 

31 25,29 

Mare F^ecunditatis, in Moon, PL 26, 27-31 ... 29 

Mare Frigoris, in Moon, PL 23, 31, 36, 38 29 

Mare Humboldtianum, in Moon, PL 23, 27, 28, 

29, 30 29 

Mare Humorum, in Moon, PL 25, 35, 36, 37, 38 29 

Mare Imbrium, in Moon, PL 24, 32-38 29 

Mare Nectaris, in Moon, PL 26, 29, 30, 31 ... 29 

Mare Nubium, in Moon, PL 25, 33, 34, 35, 36, 37 29 
Mare Tranqutllitatis, in Moon, PL 23, 29, 30, 

31 29 

Mare Serenitatis, in Moon, PL 23, 30, 31, 32.. 29 

Mare Smythh, in Moon, PL 23, 27 29 

Mare Vaporum, in Moon, PL 23, 31 29 

M arlnus, Lunar Object No. 18, PL 26 26 



INDEX. 



11 



PAGE 

Marius, Lunar Object No. 390, PI. 24, 36 28 

Mars, at Eastern Quadrature, PL 8. 
Mars, at greatest distance, PI. 8. 
Mars, at least favourable opposition, PI. 8. 
Mars, at most favourable opposition, PI. 8. 
Mars, at Western Quadrature, PI. 8. 
Mars, Chart of, PI. 9. 

Mars, Dimensions, &c 4 

Mars, How to find 35 

Mars in Opposition 33 

Mars, Orbit of, PL 2, 3. 
Mars, Periodic time of, PL 2. 
Mars, Phases of, PL 8. 
Mars, Satellites of, PL 6. 

Maskelyne, Lunar Object No. 157, PL 23 27 

Mason, Lunar Object No. 213, PL 23 27 

Maunder, on Mars 9 

Maupertuis, Lunar Object No. 424, PL 24 28 

Maurolychus, Lunar Object No. 121, PL 26, 

30,31 26 

Maury, Lunar Object No. 223, PL 23 27 

McClure, Lunar Object No. 37, PL 26 26 

Mean Distance of a Planet 2 

Medh Sinus, in Moon, PL 24, 32, 33, 34 29 

Medusa, PL 3 3 

Menelaus, Lunar Object No. 234, PL 23, 31 ... 27 
Mensa, PL 70. 

Mercator, Lunar Object No. 339, PL 25, 34 ... 28 
Mercurius, Lunar Object No. 180, PL 23, 27, 28 27 

Mercury, as a Morning Star 33 

Mercury, as an Evening Star 33 

Mercury, Dimensions of, PL 4 4 

Mercury, Orbit of, PL 2. 
Mercury, Periodic time of, PL 2. 

Mercury, when to be seen 33 

Meridian. — At any place the Celestial Meridian 
is the great circle through the Poles and the 
Zenith. 
Meridian (Central). — Means in this Atlas the 
line joining the North point to the South 
point on the monthly maps. 

Merope, in Pleiades, PL 12 10 

Mersenius, Lunar Object No. 350, PL 25, 36, 37 28 
Messala, Lunar Object No. 175, PL 23, 27, 28... 27 
Messier, Lunar Object No. 29, PL 26, 28, 29 ... 26 

Metius, Lunar Object No. 44, PL 26, 28, 29 26 

Meton, Lunar Object No. 197, PL 23, 30 27 

Milichius, Lunar Object No. 379, PL 24, 35 ... 28 
Micrometer — An instrument for the measure- 
ment of small quantities. 
Microscopium, PL 69. 



PACE 

Miller, Lunar Object No. 134, PL 26 26 

Mimas, Satellite of Saturn, PL 6 6 

Mitchell Mountains, on Mars, PL 9. 

Moigno, Lunar Object No. 195, PL 23 27 

Monoceros, PL 59, 60. 

Monocerotis, S. , regularly Variable Star, PL 59 41 

Monocerotis, T, regularly Variable Star, PL 59 41 

Monocerotis, II, a Triple Star, PL 59 51 

Monthly Maps of Stars, PL 39-50 30 

Moon, Eclipsed by Earth, PL 7. 
Moon, Elger's drawings of, PL 23-38. 
Moon, Key Maps of Objects, PL 27-38. 

Moon, List of Lunar Objects 26-29 

Moon, List of Mountain Ranges 29 

Moon, List of Seas in 29 

Moon, Mountains near limb of 29 

Moon, Orbit of, PL 6. 

Moon, Plates of, at different Phases, PL 27-38. 

Moon, Sectional Charts of, PL 23-26. 

Moon, Table for finding Place with Age 23 

Moon's Phases and Eclipses, PL 7. 

Moretus, Lunar Object No. 300, PL 25, 32, 33 28 

Mortis Lacus, in Moon, PL 23, 29, 30, 31 29 

Mosting, Lunar Object No. 261, PI, 25, 32, 33.. 27 

Musca, PL 67, 70. 

Mutus, Lunar Object No. 53, PL 26, 29 26 

Nadir. — The point of the celestial sphere be- 
neath our feet to which a plummet points. 

Nasireddin, Lunar Object No. 287, PL 25 27 

Nasmyth Inlet, in Mars, PL 9. 

Nautical Almanac (quoted) 2 

Neander, Lunar Object No. 43, PL 26, 28 26 

Neap Tide, Cause of, PL 5 5 

Nearchus, Lunar Object No. 50, PL 26 26 

Nebula. — A faint extended luminosity on the 
heavens, visible in a telescope. 

Nebula, Great, in Andromeda, PL 14, 52 16, 46 

Nebula, Great, in Orion, PL 14, 59 16, 50 

Nebula H 527, in Andromeda, PL 52, 53 48 

Nebula H 1157, in Taurus, PL 53, 59 50 

Nebula H 2102, Planetary, in Hydra, PL 60 ... 53 

Nebula H 2343, Planetary, in Ursa Major, PL 55 53 

Nebula H 2838, Spiral, in Virgo, PL 60, 61 ... 53 

Nebula H 3321, in Coma Berenicis, PL 55, 61... 54 

Nebula H 3453, in Coma Berenicis, PL 61 54 

Nebula H 3572, in Canes Venatici, PL 55 54 

Nebula H 3636, in Canes Venatici, PL 55 54 

Nebula H 4373, in Draco, PL 51, 56, 57 56 

Nebula H 4403, in Sagittarius, PL 62 56 

Nebula H 4447, Annular, in Lyra, PL 57 56 



12 



INDEX. 



PAGE 

Nebula H 4532, in Vulpecula, PI. 57, 62 56 

NEBUL2E H 1949, 1950, in Ursa Major, PI. 51, 54 53 
Nebularum Palus, in Moon, PL 23, 31, 32 ... 29 
Nectaris Mare, in Moon, PL 26, 29, 30, 31 ... 29 

Neper, Lunar Object No. 139, PL 23, 27 27 

Neptune, Dimensions of, PL 4 4 

Neptune, Orbit of, PL 3 3 

Neptune, Satellite of, PL 6 6 

Newcomb, Lunar Object No. 225, PL 23 27 

Newton, Lunar Object No. 302, PL 25, 34 28 

Newton Sea, in Mars, PL 9. 
New Moon, PL 7. 

Nicolai, Lunar Object No. 69, PL 26 26 

Nicollet, Lunar Object No. 344, PL 25, 33 28 

Niesten Isthmus, on Mars, PL 9. 
Noble Cape, on Mars, PL 9. 
Node. — The point in which an Orbit intersects 
the plane to which it is referred. 

Nonius, Lunar Object No. 117, PI. 26 26 

Norma, PL 68. 

Nova, 1572, irregularly Variable Star, PL 52 ... 41 
Nova, 1604, irregularly Variable Star, PL 62 . . . 42 
Nova, 1670, irregularly Variable Star, PL 57 ... 42 
Nova, 1848, irregularly Variable Star, PL 62 ... 42 
Nova, 1860, T Scorpii, irregularly Variable Star, 

PL 62 42 

Nova, 1866, T Coronae, irregularly Variable Star, 

PL 56 42 

Nova, 1876, irregularly Variable Star, PL 57 ... 42 

Nova, 1885, irregularly Variable Star 41 

Nubium Mare, in Moon, PI. 25, 33, 34, 35, 36, 37 29 
Nutation. — A small oscillation in the direction 
of the Earth's axis, due to the fact that the 
forces producing precession do not act uni- 
formly. 

Oberon, Satellite of Uranus, PL 6. 

Oblate. — Applied to a globular body flattened at 

the poles, like the Earth. 
Obliquity of the Ecliptic. —The inclination of 

the annual track of the Sun to the Equator. 

Observatory, Companion to the (quoted) 46 

Occultation. — Applied to the passage of the 

Moon over a star, or of Jupiter over one of 

his satellites. 
Oceanus Procellarum, in Moon, PL 24, 35, 36, 

37, 38 , 29 

Octans, PL 70. 

O^nopides, Lunar Object No. 435, PL 24 28 

Oersted, Lunar Object No. 183, PL 23 27 

Oken, Lunar Object No. 20, PL 26 26 



PAGE 

Olbers, Lunar Object No. 393, PL 24, 38 28 

Ophiuchi, a, a Double Star, PL 62 55 

Ophiuchus, PL 62, 68, 71, 72. 

Ophiuchus, Cluster H 4256 in, PL 62 55 

Opposition. — Applied to two planets when at 

opposite sides of the Sun. 

Opposition of Jupiter, to 1902 33 

Opposition of Mars, to 1902 33 

Opposition of Saturn, to 1902 33 

Orbit. — The track pursued by a planet round 

the Sun, or by a Satellite round its primary 

planet. 

Orbit of a Binary Star, PL 13 12 

Oriani, Lunar Object No. 163, PL 23 27 

Orion, PL 59, 71, 72. 

Orion, Great Nebula in, PL 14,.; 16, 50 

Orionis, a, or Betelgeux, PL 59 51 

Orionis, /3, or Rigel, PL 59 50 

Orionis, 3, Double Star, PL 59 50 

Orionis, 39, or X, Double Star, PL 59 50 

Orionis, <r, Multiple Star, PL 59 51 

Orionis, ?, Triple Star, PL 59 51 

Orionis, 32, Double Star, PL 59 50 

Orionis, U, regularly Variable Star, PL 59 41 

Orontius, Lunar Object No. 288, PL 25 27 

Oudeman Sea, in Mars, PI. 9. 

Palitzch, Lunar Object No. 9, PL 26 26 

Pallas, Lunar Object No. 375, PL 24, 32 28 

Palus Nebularum, in Moon, PL 23, 31, 32 29 

Palus Putredinis, in Moon, PL 23, 32 29 

Palus Somnii, in Moon, PL 23, 28, 29 29 

Parallax. — The difference in direction between 
the positions of a heavenly body as seen 

from two different points, PL 1 2 

Parallels. — Circles parallel to the Equator, 
having one of the Poles as centre. 

Parrot, Lunar Object No. 108, PL 26 26 

Parry, Lunar Object No. 271, PL 25, 33 27 

Partial Eclipse, PL 7 6 

Path of Moon, PL 7. 

Paths of Spots across the Sun's Disc, PL 18 . 17 

Pavo, PL 68, 69, 70, 72. 

Pavonis, k, regularly Variable Star, PL 69, 70... 41 

Pegasus, PL 52, 57, 58, 63, 71, 72. 

Pegasus, Cluster H 4670 in, PL 63 57 

Peirce, Lunar Object No. 153, PL 23, 27, 28, 29 27 

Pentland, Lunar Object No. 131, PL 26 26 

Percy Mts. , in Moon, PL 25 29 

Perihelion of a Planetary Orbit 2 



INDEX. 



13 



PAGE 

Periodic Time op a Planetary Orbit 2 

Persei, (3, or Algol, regularly Variable Star, 

PI. 53 41, 49 

Persei, 9, a Triple Star, PL 53 49 

Persei, p, regularly Variable Star, PI . 53 41 

Perseids, Orbit of, PI. 2. 

Perseids, Shooting Stars 3 

Perseus, PI. 52, 53, 71 . 

Perseus, Great Clusters in, PI. 52, 53 48 

Perturbation. — A disturbance in the orbit of a 
heavenly body caused by some other attrac- 
tion besides that which chiefly controls the 
motion. 

Petavius, Lunar Object No. 7, PL 26, 27, 28, 29 26 

Peters, Lunar Object No. 196, PL 23 27 

Phases of the Moon, PL 7 6 

Phases of the Planets, PL 8 6 

Phillips Island, in Mars 9 

Phillips Land, on Mars, PL 9. 

Phillips, Lunar Object No. 13, PI. 26 26 

Philolaus, Lunar Object No. 420, PI. 24, 34, 35, 

36 28 

Phobos, Satellite of Mars, PI. 6 .., 5 

Phocylides, Lunar Object No. 321, PI. 25, 36, 

37, 38. 28 

Phcenix, PL 64, 65, 72 

Piazzi, Lunar Object No. 329, PL 25, 37, 38 ... 28 

Picard, Lunar Object No. 152, PI. 23, 27, 28, 29 27 

Piccolomini, Lunar Object No. 63, PI. 26, 29, 30 26 
Pickering, Professor. See Preface. 

Pico, Lunar Mountain, PL 24, 33, 34, 35 29 

Pictet, Lunar Object No. 289, PL 25 28 

Pictor, PL 65, 66. 

PiNGRe, Lunar Object No. 319, PI. 25 28 

Pisces, PI. 52, 58, 63, 71, 72 3 

Piscis, PL 64, 69, 72. 

Piscium, 19, irregularly Variable Star, PL 58, 63 42 

Piscium, 34, Double Star, PI. 58, 63 46 

Piscium, 35, Double Star, PL 58, 63 , 46 

Piscium, 38, Double Star, PL 58, 63 46 

Piscium, 42, Double Star, PL 58, 63 46 

Piscium, a , Double Star, PL 58 48 

Piscum, <p, Double Star, PL 52, 58 47 

Pitatus, Lunar Object No. 280, PL 25, 33 27 

Pitiscus, Lunar Object No. 52, PI. 26, 29 26 

Piton, Lunar Mountains, PL 24, 34, 35 29 

Plana, Lunar Object No. 214, PI. 23, 29 27 

Plane of Ecliptic, PL 1. 

Plane of Equator, PL 1. 

Plane of Rational Horizon, PL 1. 

Planets, Inner, PL 2 2 



PAGE 

Planets, Comparative Sizes of, PI. 4 4 

Planet, Mean Distance of a 2 

Planetary Nebula, in Hydra, H 2102, PL 60. . . 53 
Planetary Nebula, in Ursa Major, H 2343, 

PL 55 53 

Planetary Nebula, in Draco, H 4373, PI. 51, 

56, 57 56 

Planetary Phases, PL 8 6 

Planetary Phenomena .... 33 

Planets, Symbols for the 3 

Plato, Lunar Object No. 413, PL 24, 32, 33, 

34, 35 ,...25, 28 

Playfair, Lunar Object No. 100, PL 26, 31 ... 26 

Pleiades.— Description of, PL 12 10 

Pleiades, Stars in the 11 

Pleiades, PL 53, 58, 71, 72. 

Plinius, Lunar Object No. 227, PL 23, 30, 31... 27 

Plutarch, Lunar Object No. 164, PL 23 27 

Poisson, Lunar Object No. 96, PI. 26 26 

Polar Axis, PL 1. 

Pole Star, as a Double Star, PL 51 47 

Polybius, Lunar Object No. 92, PL 26 26 

Pons, Lunar Object No. 93, PL 26, 30 26 

Pontanus, Lunar Object No. 94, PI. 26 26 

PoNTecouLANT, Lunar Object No. 22, PL 26, 27, 

28 26 

Posidonius, Lunar Object No. 218, PL 23, 29, 

30 27 

Position Angle of the Sun's Axis 18 

Pr^sepe Cancri— a Cluster, PI. 54, 60 52 

Pratt Bay, in Mars, PL 9. 

Precession in Declination, Table of 45 

Precession in R. A., Table of 44 

Precession of the Equinoxes. — An alteration 

in the position of the Equinoxes, due to a 

continuous revolution of the pole of the 

Equator round the pole of the Ecliptic, in 

about 26,000 years. 
Prime Vertical, PI. 1. 

Pritchard, Positions of the Pleiades 10 

Procellarum Oceanus, in Moon, PI. 24, 35, 36, 

37, 38 29 

Proclus, Lunar Object No. 156, PL 23, 28, 29.. 27 
Proctor on Saturn. See Preface. 
Proctor Cape, on Mars, PL 9. 

Prominences on the Sun, PL 17 17 

Promontory, Laplace, in Moon, PL 24, 34, 35, 

36, 37 29 

Ptolem;eus, Lunar Object No. 264, PL 25, 32, 33 27 

Puppis L 2 , regularly Variable Star, PL 66 41 

Puppis, PL 59, 60, 66. 



14 



INDEX. 



FAGE 

Purbach, Lunar Object No. 277, PL 25, 32 27 

Putredtnis Palus, in Moon. PL 23. 32 29 

Pyrenees, in Moon, PL 26, 28, 29, 30 29 

Pythagoras, Lunar Object No. 432, PL 24. 37, 

35 2S 

Pytheas, Lunar Object No. 403, PL 24, 33, 34 28 

Quadrature. — The position of a heavenly body 

when 90° from the Sun 7 

Rabbi Levi, Lunar Object No. 66, PL 26, 30 ... 26 
Radiant Point. — The point on the heavens from 

which the Shooting Stars, in a shower of 

such bodies, appear to diverge 42 

Rambaut, Dr. Arthur A. See Preface. 

Ramsden, Lunar Object No. 355, PL 25, 34, 35 28 
Ranyard, Mr. A. Cowper. See Preface. 
Rational Horizon, PL 1. 

Reaumur, Lunar Object No. 115, PL 26 - 

Red Spot on Jupiter, PL 10 9 

Refraction. — The bending of a ray of light on 

ssiiig from one medium into another 1 

Refractions, Table of 1 

Regiomontanus, Lunar Object No. 275, Pi. 25, 

32 27 

Regularly Variable Stars 41 

Retchenbach, Lunar Object No. 41, PL 26, 28 26 

Retner, Lunar Object No. 359, PL 24, 36 •_ 5 

Retnhold, Lunar Object No. 377, PL 24, 33, 34, 

35 28 

Repsold, Lunar Object No. 439, PI. 24, 38 29 

Reticulum, PL 65. 70 

Retrograde. — Applied to a planet which seems 

to move from east to t : ; : . 

Rileticus, Lunar Object No. 114, PL 26, 31 ... 26 

Rbea, Satellite of Saturn, PL 6 6 

Rheita, Lunar Object No. 42, PL 26 26 

Ricctoli, Lunar Object No. 365. PL _: 38 28 

Riccius, Lunar Object No. 65, PL 26, 30 26 

Rigel, or /3 Orionis, PL 59 50 

RlGEC ASCEHHIOB 1 

Ring Nebula ln Lyra, H 4447, PL 57 56 

RiprLEAN Mountains, in Moon, PL 25, 35 29 

Ritter, Lunar Object No. 246, PL 23, 30 27 

Roberts, Isaac, Dr. — Photographs of Nebula; 16 

Robinson, Lunar Object No. 436, PL 24 25 

Rocca, Lunar Object No. 362, PI. 25, 37, 38 25 

Romer, Lunar Object No. 221, PL 23 27 

Rook Mountains, Lunar Object 29 

Roris Sinus, in Moon, Pi. 24, 37, 35 29 



PAGE 

EosENBERGER, Lunar Object No. 49, PL 26, 28, 

29 26 

Ross, Lunar Object No. 228, PL 23, 30 27 

I. 3SSB Land, on Mars, PL 9. 

-z, Lunar Object No. 61, PL 26 26 

Rost, Lunar Object No. 315, PL 25, 34, 35 28 

Roiation Period of Jupiter, PL 4 4 

Rotation Period of Planetary System, PL 4 4 

Rotation Period of Saturn, PL 4 4 

Sabine, Lunar Object No. 247, PL 23, 30 27 

Sacrobosco, Lunar Object No. 90, PL 26, 30 ... 26 
Sagltta, PL 62, 63. 

Saglttarii, 3, regularly Variable Star, PL 68 ... 41 
Sagittarii, y%% regularly Variable Star, PL 68, 

69 41 

SAGrnARius, PL 62, 68, 69, 72 3 

Sagittarius, Nebula IJ 4403 in, PL 62 56 

Sagittarius, Cluster H 4406 in, PL 62, 69 56 

Sanibech, Lunar Object No. 36, PL 26, 28, 29.. 26 

Sasskeee z-. Lunar Object No. 284, PL 25, 33 ... 27 

Satellite of Neptune, PL 6 6 

Satellites of Jupiter, PL 6 5 

Satellites of Mars, PL 6 5 

Satellites of Saturn, PL 6 6 

Satellites of Uranus, PL 6 6 

Sasklkeeeg systems of, PL 6 5, 6 

^_itrn, Description of Orbit of . PL 3 4 

Saturn. — Description of, PL 11 10 

Saturn. — Dimensions of Dusky Ring, PL 4. 
Saturn. — Dimensions of inner bright Ring, PL 4. 
Saturn. — Dimensions of outer bright Ring, PL 4. 
Saturn, Drawings of, PL 11. 

Saturn ln Opposition, to 1902 33 

Saturn, Index to 37 

Saturn, Orbit of, PL 3. 

Saturn, Phases of, PL 8 8 

Saturn, Satellites of, PL 6 6 

5^-iTRN, as seen from Ms Axis produced, PL 4. 
Saxdbb, as seen from line of Nodes of his Equa- 
tor. PL 4. 

Saussure, Lunar Object No. 290, PL 25, 32, 33 28 

Schelner, Lunar Object No. 313, PL 25, 34, 35 28 

ScHiAPARELLi, Lunar Object No. 450, PL 24 29 

Schiaparelli, Views of Mars 9 

ScETAPARELLi Lake, in Mars, PL 9. 
Schickard, Lunar Object No. 323, PL 25, 36, 

37, 38 28 

Schxller, Lunar Object No. 317, PL 25, 35, 36 28 
ScHJELLERUP, No. 152, irregularly Variable 

Star........ 42 



INDEX. 



15 



PAGE 

Schmidt Bay, in Mars, PL 9. 

Schomberger, Lunar Object No. 27, PI. 26, 29 26 

Schroter, Lunar Object No. 374, PI. 24, 32 28 

Schroter Sea, in Mars, PI. 9. 

Schubert, Lunar Object No.. 135, PI. 23 26 

Schumacher, Lunar Object No. 178, PI. 23 27 

Schwabe, Lunar Object No. 149, PI. 23 27 

Scientific Enquiry, Admiralty Manual of... 42 

Scoresby, Lunar Object No. 202, PI. 23, 30 27 

SCORPH, T, Nova (1860), irregularly Variable 

Star, PI. 61, 62, 68 42 

Scorpii, or, or Antares, PI. 68 55 

Scorpio, PI. 61, 62, 68, 72 3 

Sculptor, PI. 58, 64. 

Sculptoris, K, regularly Variable Star, PL 64.. 41 

Seasons, Cause of, PL 5 4 

Secchi, Le Soliel. See Preface. 

Secchi, Lunar Object No. 155, PL 23, 28 27 

Secchi Continent, on Mars, PL 9. 

Segner, Lunar Object No. 311, PL 25, 35 28 

Seleucus, Lunar Object No. 397, PL 24, 37, 38 28 

Seneca, Lunar Object No. 165, PL 23 27 

Sensible Horizon, PL 1. 

Serenitatis Mare, in Moon, PL 23, 30, 31, 32.. 29 

Serpens, PL 56, 61, 62, 71, 72. 

Serpentis, 8, a Double Star, PL 61 55 

Sextans, PL 60. 

Sextantis 35, a Double Star, PL 60 53 

Sharp, Lunar Object No. 426, PL 24, 35, 36 28 

Short, Lunar Object No. 301, PL 25 28 

Shuckburgh, Lunar Object No. 184, PL 23 27 

Silberschlag, Lunar Object No. 252, PL 23 ... 27 

Simpelius, Lunar Object No. 133, PL 26 26 

Sinus ^Estuum, in Moon, PL 24, 32, 33, 34 29 

Sinus Iridum, in Moon, PI. 24, 34, 35, 37, 38 ... 29 
Sinus Iridum Highlands, in Moon, PL 24, 35, 

36, 37 29 

Sinus Medii, in Moon , PL 24, 32, 33 29 

Sinus Boris, in Moon, PL 24, 37, 38 29 

Sirsalis, Lunar Object No. 358, PL 25 28 

Smyth, Piazzi, Lunar Object No. 412, PL 24 ... 28 

Smythii Mare, in Moon, PL 23, 27 29 

Smyth's Celestial Cycle 46 

Snellius, Lunar Object No. 16, PL 26, 28 26 

Solar Corona, Description of, PL 17 17 

Solar Maps, Description of 17-21 

Solar Maps, PL 17, 18, 19, 20, 21, 22. 

Solar Phenomena, Corona and Prominences, 

PL 17 17 

Solstices. — The points of the Ecliptic attained 



PAGE 

by the Sun at Midsummer and Midwinter, 

PL 2. 

Sommering, Lunar Object No. 373, PL 24, 32 ... 28 

Somnii Palus, in Moon, PL 23, 28 29 

Somniorum Lacus, in Moon, PL 23, 29, 30, 31... 29 

Sosigenes, Lunar Object No. 230, PL 23 27 

South, Lunar Object No. 433, PL 24 28 

Sphere, Circles of the, PL 1. 

Sphere of the Heavens 1 

Spherical Astronomy, Briinnow's 10 

Spiral Nebula, in Virgo, H 2838, PL 60, 61 ... 53 

Spot on Sun, PL 17 17 

Spring Tide, PL 5 5 

Stadius, Lunar Object No. 381, PL 24, 33 28 

Starland. — Quoted in Preface. 
Star Maps, PL 51-72. 

Star Maps, Description of 39-45 

Stars, Variable, List of 41 

Stars in the Pleiades, PL 12 11 

Steinheil, Lunar Object No. 47, PL 26 26 

Stevinus, Lunar Object No. 15, PL 26, 28 26 

Stiborius, Lunar Object No. 64, PL 26, 29, 30 26 

Stofler, Lunar Object No. 119, PL 26, 31 26 

Strabo, Lunar Object No. 190, PL 23 27 

Straight Bange, Lunar Mountains, PL 24 29 

Straight Wall, Lunar Object No. 275, PL 25, 

33 27 

Street, Lunar Object No. 295, PL 25 28 

Struve, Otto, Lunar Object No. 446, PL 24, 38 29 
Sulpicius Callus, Lunar Object No. 235, PL 23, 

31 27 

Summer Solstice, PL 2. 

Sun, Cause of Seasons, PL 5. 

Sun, Charts for observing Spots on, PL 19-22 ... 19 

Sun, Corona of, PL 17 17 

Sun, Eclipse of, PL 7 6 

Sun, Equator of, and measurement of longitudes 19 
Sun, Method of finding the place of Sun Spots, 

PL 19-22 19 

Sun, Mr. Arthur Thomson's system of Charts, 

PL 19-22 19 

Sun, Node of Solar Equator, PL 2. 

Sun, Paths of Spots across face, PL 18 17 

Sun, Period of Botation 18 

Sun, Photograph of Sun Spot by Janssen, PL 17 17 

Sun, Position of, each month 17 

Sun, Prominences surrounding, PL 17 17 

Sun, Table of heliographic longitude of centre... 20 

Sun Spot, Drawings of, PL 17 17 

Systems of Satellites, PL 6. 



16 



INDEX. 



PAGE 

Tacitus, Lunar Object No. 82, PI. 26, 30 26 

Tail of a Comet, PI. 10 9 

Tannerus, Lunar Object No. 145, PI. 26 27 

Taquet, Lunar Object No. 233, PI. 23, 31 27 

Taruntius, Lunar Object No. 154, PI. 23, 28, 29 27 

Tauri, a, or Aldebaran, PI. 59 49 

Tauri, X, regularly Variable Star, PI. 58, 59 ... 41 

Taurus, Lunar Mountains, PI. 29, 30, 31 29 

Taurus, PI. 53, 58, 59, 71, 72 3 

Taurus, Nebula H 1157 in, PI. 53, 59 50 

Taylor, Lunar Object No. 76, PI. 26 26 

Telescopium, PI. 68, 69. 

Teneriffe Range, Lunar Mountains, PL 24 ... 29 

Terby, Views of Mars , 9 

Terby Sea, in Mars, PI. 9. 

Terminator of Moon , 24 

Tethys, Satellite of Saturn, PI. 6 6 

Thales, Lunar Object No. 191, PI. 23 27 

THEiETETUS, Lunar Object No. 257, PI. 23, 31, 32 27 

Thebit, Lunar Object No. 274, PI. 25, 32, 33 ... 27 

Theon, jun., Lunar Object No. 75, PL 26 26 

Theon, sen., Lunar Object No. 74, PI. 26 26 

Theophilus, Lunar Object No. 79, PL 26, 30 ... 26 

Thomson, Prof. Arthur, Sun Charts 19 

Tides, PL 5 4, 5 

Tim;eus, Lunar Object No. 414, PL 24, 32 28 

Timocharis, Lunar Object No. 401, PL 24, 33, 

34,35 28 

Timoleon, Lunar Object No. 147, PL 23 27 

Titan, Satellite of Saturn, PL 6 6 

Titania, Satellite of Uranus, PL 6 6 

Tobias Mayer, Lunar Object No. 384, PL 24, 

34,35 28 

Torricelli, Lunar Object No. 56, PL 26 26 

Total Eclipse of Sun, PL 7 6 

Tralles, Lunar Object No. 168, PL 23, 28 27 

Tranquillitatis Mare, in Moon, PL 23, 29, 

30, 31 29 

Transit. — The passage of a celestial body across 

a fixed line, of a planet across the Sun, or of 

one of his satellites across Jupiter. 
Triangula, PL 52, 53, 71. 

Trianguli i, a Double Star, PL 52, 53 48 

Triangulum, PL 68, 70, 72. 

Triesnecker, Lunar Object No. 242, PL 23, 31, 

32 27 

Tropic of Cancer, PL 1. 5 4 

Tropic of Capricorn, PL 1, 5 4 

Trouvelot, Drawing of Coggia's Comet, PL 16 16 
Trouvelot Bay, in Mars, PI. 9. 
Tucana, PL 70. 



Turner, Mr. H. H. See Preface. 

Tycho, Lunar Object No. 291, PL 25 ; 33, 34 

Tycho Sea, in Mars, PL 9. 



28 



Ukert, Lunar Object No. 241, PL 23 27 

Ulugh Beigh, Lunar Object No. 443, PL 24 29 

Umbriel, Satellite of Uranus, PI. 6 6 

Urs-E Majoris, 65, a Double Star, PL 55 53 

Urs^i Majoris, £, a Double Star, PL 55 53 

Urs^j Majoris, ?, a Double Star, PL 55 54 

Ursa Major, PL 51, 54, 55, 56, 71. 

Ursa Major, H 1949, 1950, Nebulae in, PL 51, 54 53 

Ursa Major, H 2343, Planetary Nebula in, 

PL 55 53 

Ursa Minor, PL 51, 56, 71. 

Unsm Minoris, a, as a Double Star, PL 51 47 

Uranometrie Generale of HOUZEAU : 40 

Uranus, Dimensions of, PL 4 4 

Uranus, Orbit of, PL 3 ". 3 

Uranus, Satellites of, PL 6 6 

Vaporum Mare, in Moon, PL 23, 31 29 

Variable Stars 41 

Vasco de Gama, Lunar Object No. 396, PL 24... 28 

Vega, Lunar Object No. 21, PI. 26 26 

Vega, or a Lyr^;, PI. 57 56 

Vela, PL 66, 67. 

Velorum N., regularly Variable Star, PL 66 ... 41 

Velorum R., irregularly Variable Stai% PL 66, 67 41 

Vendilinus, Lunar Object No. 3, PL 26, 27, 28, 29 26 

Venus, as a thin Crescent, PL 8 7 

Venus, as an Evening Star 33 

Venus, as a Morning Star 33 

Venus, at its greatest brilliance, PL 8 7 

Venus, at Inferior Conjunction 7 

Venus, at Superior Conjunction, PL 8 7 

Venus, Dimensions of, and position of Axis, PL 4 4 

Venus, how to find 34 

Venus, just before Inferior Conjunction, PL 8. 
Venus, Orbit of, PL 2. 
Venus, Periodic Time of, PL 2. 

Venus, when gibbous, PL 8 8 

Vertical, Prime, PL 1. 

Vieta, Lunar Object No. 332, PL 25, 36, 37 ... 28 

Virginis S., regularly Variable Star, PL 61 41 

Virginis y, a Double Star, PL 61 54 

Virgo, PI. 60, 61, 71, 72 3 

Virgo, H 2838, Spiral Nebula in, PL 60, 61 ... 53 

Virgo, H 3900, Cluster in, PL 61 54 

Vitello, Lunar Object No. 335, PL 25, 35 28 



INDEX. 



17 



PAGE 

Vitrttvius, Lunar Object No. 159, PL 23, 29 ... 27 

Vlacq, Lunar Object No. 48, PL 26, 29 26 

Volans, PI. 66, 70. 
Vulpecula, PI. 57, 62, 63. 

Vulpecula, H 4532, Nebula in, PI. 57, 62 56 

Vulpecula T. , regularly Variable Star, PI. 57 41 

Walter, Lunar Object No. 116, PI. 26, 32 26 

Wargentln, Lunar Object No. 322, PI. 25, 37, 38 28 

Webb, Celestial Objects for Common Telescopes 42 

Webb, Lunar Object No. 2S, PI. 26 26 

Webb Land, on Mars, PI. 9. 

Weigel, Lunar Object No. 314, PI. 25 28 

Werner, Lunar Object No. 98, PI. 26, 31, 32 ... 26 

Whewell, Lunar Object No. 255, PL 23 27 

Wichmann, Lunar Object No. 369, PL 25, 35 ... 28 

Wilhelm I., Lunar Object No. 293, PL 25, 33, 34 28 
Wilhelm Humboldt, Lunar Object No. 12, PL 

26, 27 26 

Wilson, Book on Double Stars 46 

Wilson, Lunar Object No. 307, PL 25, 35 28 



Wolf, Positions of the Pleiades ] 

Wollastox, Lunar Object No. 449, PL 24, 36... 29 

Wrottesley, Lunar Object No. 8, PL 26 26 

Wurzelbauer, Lunar Object No. 2S3, PL 25, 33 27 

Xenophanes, Lunar Object No. 438, PL 24, 38 28 

Zach, Lunar Object No. 129, PL 26, 31, 32 26 

Zagut, Lunar Object No. 67, PL 26, 30 26 

Zenith.— The point of the celestial sphere di- 
rectly overhead to which a plumb line 
points. 

Zeno, Lunar Object No. 148, PL 23 27 

Zodiac. — A belt on the heavens within which 
the larger planets chiefly remain. It is 
practically what is marked on the Monthly 
Maps as the "Track of the Planets." 

Zodiac, Signs of the 3 

Zollner Sea, in Mars, PL 9. 

Zuchtus, Lunar Object No. 310, PL 25 28 

Zupus, Lunar Object No. 360, PL 25 28 






DEC -o m 



